The effect of trypsin of rate, force and cyclic AMP in guinea pig atria.

Trypsin (10(-6)M produced a positive inotropic and chronotropic effect in left and right atria respectively and an increase in cyclic AMP. The effects were blocked by aprotinine while propranolol, phentolamine, promethazine and cimetidine and reserpine pretreatment did not alter trypsin activity. Trypsin effects were potentiated by RO 20,1724, a phosphodiesterase inhibitor. The cardiac effects of trypsin may be due to increase in cyclic AMP and are in agreement with previous work indicating that trypsin can activate cardiac adenylate cyclase.