Dear Siti,

The following text covers the answer to your question.

PRESSURE MYOGRAPH SYSTEMS - GENERAL

http://www.dmt.dk/default.asp?Action=Details&Item=338

The Pressure myograph systems are used to measure the physiological function and properties of small arteries, veins and other vessels. The system also allows the study of pharmacological effects of drugs and other vasoactive compounds on small isolated vessels under near physiological conditions. In these systems, vessels retain many of their in vivo characteristics.

In pressure myography, an intact small segment of an artery or vein is mounted onto two small glass cannulae and pressurized to a suitable transmural pressure. This near physiological condition permits the investigation of intrinsic (myogenic) responses which can be extrapolated to the in vivo behaviour of the entire vascular bed (autoregulation).

Various pharmacological agents can then be studied by adding these to the superfusate or luminal solution. Both constriction and dilation can be readily measured as changes in diameter of the preparation via digital video edge-detection. Since intrinsic myogenic constriction is present, the role and function of the endothelium for this phenomenon can be studied.

Specialized versions of pressure myograph chambers can accommodate special research need like imaging (confocal) or electrophysiology. Pressure-based culture myographs are a new tool that provides long term tissue preservation to study molecular changes introduced via viral vectors, siRNA or other interventions. In this way, mechanistic and molecular physiological and pharmacological studies can be done on intact tissue under near physiological conditions. Overall the pressure myograph technique is a very powerful tool in the hands of the dedicated vascular physiologist or pharmacologist.

The following lists are a few of the established areas of investigation for the pressure myograph systems. In the future, many more areas will be added to these lists through ongoing product development and the research performed by myograph users.

BASIC PROPERTIESSmall vessel function, vascular diameter

Vascular smooth muscle function

Vascular endothelium function

Wall tension & thickness measurements

Vessels isolated from animal or human

Assessment of local vascular reactivity

VASOACTIVE MECHANISMS

Endothelium: role of endothelium-derived relaxing factor (NO), prostaglandins and endothelium-derived hyperpolarizing factor (EDHF)

Smooth muscle: role of calcium and potassium and other ion channels

Perivascular and intramural nerves: role of endogenous released transmitters

PHYSIOLOGICAL CHANGES

Aging

Pregnancy

Preeclampsia

PHARMACOLOGY & PHARMACOTHERAPY

Quantify the effect of treatment with e.g. ACE- inhibitors, statins, glitazones or insulin

Receptor studies, localization and characterization of receptors

Affinity and efficacy studies of vasoactive agonists and antagonists

PATHOLOGY

Hypertension

Atherosclerosis

Diabetes

Ischemia, heart disease and heart failure

Tumors and angiogenesis

Heart and lung diseases

FURTHER POSSIBILITIES

Electrophysiological experiments (flexible electrodes)

Fluorescence measurements of intracellular ions and other substance

FEATURES & BENEFITS

This specialty line of myographs is mostly used to study small vessel function under near physiological conditions of pressure and flow by digital tracking of diameter and flow in time

The products include single artery systems called myographs for diameter measurement under user controlled pressure and flow conditions. Specialty versions include confocal, freeze/fix and culture myographs. The latter are used to bring the advances of molecular biology (siRNA, viral transduction) to the study of small Vessel function

Applications studies are not limited but include vascular myogenic tone regulation, endothelial function and effects of shear, calcium imaging in the arterial wall myocytes and multi-day studies of reactivity after transduction or pharmaco-logical treatment

DMT Pressure Myographs can be expanded with a FlowMeter or luminal drug infusion or sampling ports

ALL PRESSURE MYOGRAPH SYSTEMS

Pressure Myograph System - 110P/110PXL

A system used to study the structure and function of isolated sections of small vessels (diameter >60 μm) under near-physiological conditions.

Pressure Myograph System for rapid freezing - 115FP

Designed for biochemical or morphological studies where rapid freezing or fixing of the intact, pressurized vessel is required.

Confocal Pressure Myograph System - 120CP

Specifically for use with laser scanning confocal microscopes and used to study intracellular ion activity and isobaric constriction of isolated sections of small resistance arteries (diameter >50 µm).

Culture Myograph System 202CM/204CM

Providing long-term functional preservation of small blood vessels by maintaining them under controlled culture conditions of intravascular pressure and flow

WIRE MYOGRAPH SYSTEM - GENERAL

http://www.dmt.dk/?Action=Details&Item=329

The Wire Myograph allows examination of small vessels (internal diameter 60 μm - 10 mm) in terms of morphology and responsiveness to hormones and other agonists.

The small vessels are mounted as ring preparations by threading them onto two stainless steel or tungsten wires and securing the wires to two supports.

One support is then attached to a micrometer, allowing control of vessel circumference. The other support is attached to a force transducer for measurement of tension development. The whole preparation is kept in a chamber with physiological salt solution at 37°C, bubbled with oxygen. Vessels maintained in Wire Myographs are viable for several hours.

Following mounting and equilibration, the passive length-tension relationships of the vessels are determined; a normalization procedure. During the actual experiments, the circumference of the vessels are kept constant and vessels are examined under isometric conditions. Compounds are added directly to the chamber and vessel tension is monitored. Furthermore, it is possible to compare vessels from patients or test groups with those of control, not only in terms of vessel reactivity to various compounds, but also in terms of morphology.

The following lists are a few of the established areas of investigation for Wire Myograph systems. Many more investigation possibilities for vascular and other smooth muscle may be added through the imagination of researchers such as yourself.

BASIC TISSUE PROPERTIESVascular smooth muscle function

Vascular endothelium function

Length-tension relationships (also motorized)

Wall tension & morphometric measurements

Assessment of pharmacological reactivity

TISSUES USEDSmall and large arteries

Veins

Lymph vessels

Lung and tracheal smooth muscle

Urogenital, corpus cavernosum, bladder

VASOACTIVE MECHANISMSEndothelium: role of endothelium-derived relaxing factor (NO), prostaglandins and endothelium-derived hyperpo-larizing factor (EDHF)

Smooth muscle: role of calcium and potassium and other ion channels

Perivascular and intramural nerves: role of endogenously released transmitters

PHARMACOLOGY & PHARMACOTHERAPY

Quantify the effect of treatment with contractile and relaxing agents

Receptor studies, localization and characterization of receptors

Affinity & efficacy studies of agonists & antagonists

Drug studies efficiency & efficacy, drug discovery & safety pharmacology                

PHYSIOLOGICAL CHANGES& PATHOLOGY 

Hypertension

Atherosclerosis

Diabetes

Ageing

Ischemic heart disease & heart failure

Tumors & angiogenesis

Gastrointestinal & urogenital disease Pregnancy, preeclampsia

Exercise physiology, muscular degenerative diseases

FURTHER POSSIBILITIES

Electrophysiological experiments

Fluorescence measurements of intracellular ions and other substances

 ALL WIRE MYOGRAPH SYSTEMS

Single Wire Myograph System - 320A

Ideal for studying a single vessel with a diameter of 60 μm - 3 mm. The vessel is mounted as a ring preparation by threading it over two parallel stainless steel wires and securing the wires to two supports or "jaws".

Dual Wire Myograph System - 420A & 520A

Simultaneous testing of two vessels with diameters of 60 μm - 3 mm, independently.

Multi Wire Myograph System - 620M

This 4-channel multi myograph system is a highly sophisticated yet robust research instrument. It is an easy-to-use system for in vitro studies of small and large blood vessels, trachea or gut mounted as larger ring preparations (up to 10 mm).

Confocal Wire Myograph System 360CW

Specially designed to provide very close optical access to the mounted artery or tissue segment, thereby allowing high resolution images of fluorescent dyes or markers by laser scanning confocal microscopy (LSCM).  

Hoping this will be helpful,

Rafik

Dear Siti,

The following text covers the answer to your question.

PRESSURE MYOGRAPH SYSTEMS - GENERAL

http://www.dmt.dk/default.asp?Action=Details&Item=338

The Pressure myograph systems are used to measure the physiological function and properties of small arteries, veins and other vessels. The system also allows the study of pharmacological effects of drugs and other vasoactive compounds on small isolated vessels under near physiological conditions. In these systems, vessels retain many of their in vivo characteristics.

In pressure myography, an intact small segment of an artery or vein is mounted onto two small glass cannulae and pressurized to a suitable transmural pressure. This near physiological condition permits the investigation of intrinsic (myogenic) responses which can be extrapolated to the in vivo behaviour of the entire vascular bed (autoregulation).

Various pharmacological agents can then be studied by adding these to the superfusate or luminal solution. Both constriction and dilation can be readily measured as changes in diameter of the preparation via digital video edge-detection. Since intrinsic myogenic constriction is present, the role and function of the endothelium for this phenomenon can be studied.

Specialized versions of pressure myograph chambers can accommodate special research need like imaging (confocal) or electrophysiology. Pressure-based culture myographs are a new tool that provides long term tissue preservation to study molecular changes introduced via viral vectors, siRNA or other interventions. In this way, mechanistic and molecular physiological and pharmacological studies can be done on intact tissue under near physiological conditions. Overall the pressure myograph technique is a very powerful tool in the hands of the dedicated vascular physiologist or pharmacologist.

The following lists are a few of the established areas of investigation for the pressure myograph systems. In the future, many more areas will be added to these lists through ongoing product development and the research performed by myograph users.

BASIC PROPERTIESSmall vessel function, vascular diameter

Vascular smooth muscle function

Vascular endothelium function

Wall tension & thickness measurements

Vessels isolated from animal or human

Assessment of local vascular reactivity

VASOACTIVE MECHANISMS

Endothelium: role of endothelium-derived relaxing factor (NO), prostaglandins and endothelium-derived hyperpolarizing factor (EDHF)

Smooth muscle: role of calcium and potassium and other ion channels

Perivascular and intramural nerves: role of endogenous released transmitters

PHYSIOLOGICAL CHANGES

Aging

Pregnancy

Preeclampsia

PHARMACOLOGY & PHARMACOTHERAPY

Quantify the effect of treatment with e.g. ACE- inhibitors, statins, glitazones or insulin

Receptor studies, localization and characterization of receptors

Affinity and efficacy studies of vasoactive agonists and antagonists

PATHOLOGY

Hypertension

Atherosclerosis

Diabetes

Ischemia, heart disease and heart failure

Tumors and angiogenesis

Heart and lung diseases

FURTHER POSSIBILITIES

Electrophysiological experiments (flexible electrodes)

Fluorescence measurements of intracellular ions and other substance

FEATURES & BENEFITS

This specialty line of myographs is mostly used to study small vessel function under near physiological conditions of pressure and flow by digital tracking of diameter and flow in time

The products include single artery systems called myographs for diameter measurement under user controlled pressure and flow conditions. Specialty versions include confocal, freeze/fix and culture myographs. The latter are used to bring the advances of molecular biology (siRNA, viral transduction) to the study of small Vessel function

Applications studies are not limited but include vascular myogenic tone regulation, endothelial function and effects of shear, calcium imaging in the arterial wall myocytes and multi-day studies of reactivity after transduction or pharmaco-logical treatment

DMT Pressure Myographs can be expanded with a FlowMeter or luminal drug infusion or sampling ports

ALL PRESSURE MYOGRAPH SYSTEMS

Pressure Myograph System - 110P/110PXL

A system used to study the structure and function of isolated sections of small vessels (diameter >60 μm) under near-physiological conditions.

Pressure Myograph System for rapid freezing - 115FP

Designed for biochemical or morphological studies where rapid freezing or fixing of the intact, pressurized vessel is required.

Confocal Pressure Myograph System - 120CP

Specifically for use with laser scanning confocal microscopes and used to study intracellular ion activity and isobaric constriction of isolated sections of small resistance arteries (diameter >50 µm).

Culture Myograph System 202CM/204CM

Providing long-term functional preservation of small blood vessels by maintaining them under controlled culture conditions of intravascular pressure and flow

WIRE MYOGRAPH SYSTEM - GENERAL

http://www.dmt.dk/?Action=Details&Item=329

The Wire Myograph allows examination of small vessels (internal diameter 60 μm - 10 mm) in terms of morphology and responsiveness to hormones and other agonists.

The small vessels are mounted as ring preparations by threading them onto two stainless steel or tungsten wires and securing the wires to two supports.

One support is then attached to a micrometer, allowing control of vessel circumference. The other support is attached to a force transducer for measurement of tension development. The whole preparation is kept in a chamber with physiological salt solution at 37°C, bubbled with oxygen. Vessels maintained in Wire Myographs are viable for several hours.

Following mounting and equilibration, the passive length-tension relationships of the vessels are determined; a normalization procedure. During the actual experiments, the circumference of the vessels are kept constant and vessels are examined under isometric conditions. Compounds are added directly to the chamber and vessel tension is monitored. Furthermore, it is possible to compare vessels from patients or test groups with those of control, not only in terms of vessel reactivity to various compounds, but also in terms of morphology.

The following lists are a few of the established areas of investigation for Wire Myograph systems. Many more investigation possibilities for vascular and other smooth muscle may be added through the imagination of researchers such as yourself.

BASIC TISSUE PROPERTIESVascular smooth muscle function

Vascular endothelium function

Length-tension relationships (also motorized)

Wall tension & morphometric measurements

Assessment of pharmacological reactivity

TISSUES USEDSmall and large arteries

Veins

Lymph vessels

Lung and tracheal smooth muscle

Urogenital, corpus cavernosum, bladder

VASOACTIVE MECHANISMSEndothelium: role of endothelium-derived relaxing factor (NO), prostaglandins and endothelium-derived hyperpo-larizing factor (EDHF)

Smooth muscle: role of calcium and potassium and other ion channels

Perivascular and intramural nerves: role of endogenously released transmitters

PHARMACOLOGY & PHARMACOTHERAPY

Quantify the effect of treatment with contractile and relaxing agents

Receptor studies, localization and characterization of receptors

Affinity & efficacy studies of agonists & antagonists

Drug studies efficiency & efficacy, drug discovery & safety pharmacology                

PHYSIOLOGICAL CHANGES& PATHOLOGY 

Hypertension

Atherosclerosis

Diabetes

Ageing

Ischemic heart disease & heart failure

Tumors & angiogenesis

Gastrointestinal & urogenital disease Pregnancy, preeclampsia

Exercise physiology, muscular degenerative diseases

FURTHER POSSIBILITIES

Electrophysiological experiments

Fluorescence measurements of intracellular ions and other substances

 ALL WIRE MYOGRAPH SYSTEMS

Single Wire Myograph System - 320A

Ideal for studying a single vessel with a diameter of 60 μm - 3 mm. The vessel is mounted as a ring preparation by threading it over two parallel stainless steel wires and securing the wires to two supports or "jaws".

Dual Wire Myograph System - 420A & 520A

Simultaneous testing of two vessels with diameters of 60 μm - 3 mm, independently.

Multi Wire Myograph System - 620M

This 4-channel multi myograph system is a highly sophisticated yet robust research instrument. It is an easy-to-use system for in vitro studies of small and large blood vessels, trachea or gut mounted as larger ring preparations (up to 10 mm).

Confocal Wire Myograph System 360CW

Specially designed to provide very close optical access to the mounted artery or tissue segment, thereby allowing high resolution images of fluorescent dyes or markers by laser scanning confocal microscopy (LSCM).  

Hoping this will be helpful,

Rafik

The short answer is that pressure myography is more physiological than wire myography, for several reasons:

It allows the study of highly relevant physiological stimuli, such as pressure-mediated myogenic tone (the myogenic response)

Sorry, not all of my answer copied across.

It also allows for the study of flow induced dilation, a highly relevant physiological stimulus. 

I think wire myography is still widely used because (if folk are honest) it is technically easier and with multimyogtaphs it allows a control and 3 variables to be studied in parallel. Drug delivery is also easier. 

However, because of cannulation pressure myography also allows you to decide how you want to deliver your drug, I.e. through the lumen or by superfusing the adventitia. Pressure myograph also allows for endothelium-selective uptake of e.g. tracker dyes, siRNAs. 

Hi Rafik.

Thanks a lot. we are doing these two kinds of myography as well. The information you provided is greatly helpful for us. Much appreciated.

Also, we are trying to record the Ca2+ signal changes together with the pressure myography, but it looks more complexed and needs more practice.

The main difference between these two techniques is that one of them you can have intraluminal pressure (pressure myography).

Pressure myography: As long as you can make a vessel to hold pressure you can use this system, you can go from small vessels (i.e. lymphatic, cerebral, epigastric vessels) to big one (i.e. femoral, renal and aortas), but the key term is "hold pressure", for some arteries you will need to tie a knot around small branches in order to get a vesses long enough to use this technique. A vital step is that you need to clean the walls of your vessel enough to avoid a noisy reading on the walls, this system track the internal diameter and both wall thickness. Once you have pressurized your vessel you can do either static or dynamic experiments. For the static experiments you can test vasoreactivity using dose-response to agonists/antagonists and also test the mechanical properties (i.e. vascular remodeling and stiffness) using intraluminal pressure increments. For the dynamic experiments you can test flow mediated dilation via shear-stress stimulation of endothelial cells to release nitric oxide.

Wire myography: You have two options wires and pins. For the smaller vessels you can use wires (i.e. mesenteric, femoral, aortic rings), unlike the pressure myograph system you don't have to worry about leaks and with cleaning the walls of your vessels, this reduces the likelihood of damage to your vessels. For the bigger vessels you can use the pins (i.e. aortic rings or vessels that you would consider small fro mice but they are considerably big in rats, pigs or human subjects). This experiments are mainly for vasoreactivity.

One last point is that with the pressure myography system you can decide how you want to stimulate your vessel, you can do it intra- or abluminally. You can image the wall components after fixing your vessels using paraformaldehyde using fluorescence microscopy, it is closer to a physiological system.

I hope it helps you or someone else that have the same question.

Francisco I. Ramirez-Perez