Dear Ahmed,

You may use the method depicted in the Materials and Methods section of the recent publication entitled " Characterization of L-type calcium channel activity in atrioventricular nodal myocytes from rats with streptozotocin-induced Diabetes mellitus" contained in the following link:

 Physiol Rep. 2015 Nov; 3(11): e12632.

Published online 2015 Nov 24. doi:  10.14814/phy2.12632

PMCID: PMC4673653

Characterization of L-type calcium channel activity in atrioventricular nodal myocytes from rats with streptozotocin-induced Diabetes mellitus

Kathryn H Yuill,1 Lina T Al Kury,2 and Frank Christopher Howarth3

Author information ► Article notes ► Copyright and License information ►

Abstract

Cardiovascular complications are common in patients with Diabetes mellitus (DM). In addition to changes in cardiac muscle inotropy, electrical abnormalities are also commonly observed in these patients. We have previously shown that spontaneous cellular electrical activity is altered in atrioventricular nodal (AVN) myocytes, isolated from the streptozotocin (STZ) rat model of type-1 DM. In this study, utilizing the same model, we have characterized the changes in L-type calcium channel activity in single AVN myocytes. Ionic currents were recorded from AVN myocytes isolated from the hearts of control rats and from those with STZ-induced diabetes. Patch-clamp recordings were used to assess the changes in cellular electrical activity in individual myocytes. Type-1 DM significantly altered the cellular characteristics of L-type calcium current. A reduction in peak ICaL density was observed, with no corresponding changes in the activation parameters of the current. L-type calcium channel current also exhibited faster time-dependent inactivation in AVN myocytes from diabetic rats. A negative shift in the voltage dependence of inactivation was also evident, and a slowing of restitution parameters. These findings demonstrate that experimentally induced type-1 DM significantly alters AVN L-type calcium channel cellular electrophysiology. These changes in ion channel activity may contribute to the abnormalities in cardiac electrical function that are associated with high mortality levels in patients with DM.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4673653/

Hoping this will be helpful,

Rafik

It is better to examine whether the compound you tested  on different types of ionic currents. To focus on specific types of ion current (L-type Ca current) may produce some of different results (i.e., it is easy to jump to the conclusion). It is better to test if it can also suppress Na or different types of K currents.