Effects of m-nisoldipine on anoxia-potentiated histamine and acetylcholine-induced contractions of the porcine isolated coronary artery.

Anoxia (95% N2 + 5% CO2) potentiated the contractile response to KCl 20 mmol/L, histamine (His) 5 mumol/L and acetylcholine (ACh) 0.5 mumol/L in isolated porcine coronary arterial rings. Calcium antagonists m-nisoldipine (m-Nis) and nisoldipine (Nis) 0.4-250 nmol/L produced a concentration-dependent decrease in both KCl, His and anoxia-potentiated KCl2 His or ACh-induced contractions. Chlorpheniramine 10 mumol/L but not cimetidine 10 mumol/L and atropine 10 mumol/L abolished contractions induced by His and ACh respectively. All 3 agents did not affect KCl response and the anoxia facilitation. Indomethacin 10 mumol/L markedly attenuated the further increase in tension by anoxia but failed to inhibit the response by these vasoconstrictors.