Influence of ischemia on [Ca2+]i transients following drug therapy in hearts from aortic constricted rats.

Intracellular calcium transients were studied prior, during and after 30 min of global ischemia in control and aortic constricted rat hearts, with and without acute treatment with verapamil. Calcium transients [Ca2+]i continued to occur in verapamil treated animals for 18-20 min following the onset of global ischemia, whereas untreated hearts demonstrated calcium transients for only 3-8 min following global ischemia. Following the onset of global ischemia calcium transients continued to occur even though there was no measurable developed pressure. When calcium transients occurred for shorter periods of time during global ischemia the rise in diastolic calcium was greater and recovery was less. Addition of bradykinin to the perfusate showed that an increase in diastolic [Ca2+]i was related to a decrease in amplitude of developed [Ca2+]i transients and a decrease in developed pressure, but not to a change in coronary flow.