When we use rat trachea and histamine to induce contraction, there was no response in rats but isolated guinea-pig trachea produced high response with histamine. Why was this?
Dear Mudhir,
The guinea pig is in general a better predictor for the airway pharmacology of different drugs/mediators. First of all the mastcells in the guinea pig (of importance to asthma) release the same mediators (histamine, leukotrienes, prostaglandins) as in humans, whereas mastcells in mice and rats primarily relase serotonin. Secondly the potencies and effects of these endogeneous mediators in the guinea pig are more comparable than rats/mice to the human responses (nicely reviewed in Pulm Pharmacol Ther. 2008 Oct;21(5):702-20). Your observation is a good example that guinea pigs are in general a better predictor than mice and rats as these two species don't respond to histamine in airway smooth muscle with a contraction.
Guinea pigs on the other hand have the disadvantage that very few molecular tools (antibodies, etc) are available.
If you want to work in the guinea pig trachea, please read in on papers from our group for the method.
Am J Physiol Lung Cell Mol Physiol. 2012 Dec 1;303(11):L956-66
Br J Pharmacol. 2013 Feb;168(4):794-806)
Because with these protocols the GP trachea is an easy to model to eather study relaxations or contractions.
Good luck with your studies!
Thank you ... very good scientific information and Knewldge
Regard