regulatory role of calcium channel blockers on spontaneous muscular activity of gastrothylax crumenifer, a rumen amphistome

major proportion of intracellular calcium (ca 2+ ) is achieved through opening of calcium channels present in the plasma membrane which play an important role in regulating neuromuscular coordination and release of neurotransmitters from nerve terminals. blockade of these calcium channels adversely affect contractile process and release of neurotransmitters in majority of the neuromuscular preparations in vitro. in present study, the cumulative addition of verapamil (10 -7 -10 -3 m) caused marked excitation in amplitude, baseline tension and frequency of spontaneous muscular activity of gastrothylax crumenifer a rumen amphistome. diltiazem (10 -6 -10 -3 m) caused a significant and concentration-dependent increase in amplitude and frequency of spontaneous muscular activity of isometrically mounted rumen amphistome. it also caused significant rise in baseline tension at 10 -5 to 10 -3 m concentrations. addition of nifedipine (10 -7 -10 -3 m) elicited significant and concentration-dependent rise in amplitude and baseline tension, as compared to control values without significantly effecting frequency of spontaneous contraction.