Effects of the calcium antagonist D 600 on changes in plasma glucose and enzyme levels produced by isoproterenol in the rat

Abstract

AbstractA model based on isoproterenol injections in the female rat was used to examine the effects of the Ca2+ antagonist methoxyverapamil (D 600) on plasma glucose and on certain plasma enzymes that are elevated during cardiac dysfunction [glutamate‐oxaloacetate transaminase (GOT), lactate dehydrogenase (LDH), α‐hydroxybutyrate dehydrogenase (α‐HBDH)]. Four hours after administration, D 600 alone (10 mg/kg, i.p.), as well as isoproterenol alone (30 mg/kg, s.c.), increased plasma glucose level. When administered simultaneously with isoproterenol, D 600 produced a synergistic effect in elevating plasma glucose level. Experimental values for plasma glucose (in mg/ml) were: control, 1.56 ± 0.04 (n = 24); isoproterenol alone, 1.84 ± 0.04 (n = 24); D 600 alone, 2.05 ± 0.12 (n = 24); D 600 + isoproterenol, 3.31 ± 0.28 (n = 24). The synergistic effect of D 600 occurred at doses of 5 and 10 mg/kg, doses at which D 600 opposed the increases in GOT, LDH, and α‐HBDH levels induced by isoproterenol. Other experiments showed that elevations in plasma glucose level produced 15 and 30 min after injection of isoproterenol were associated with increases in plasma insulin levels.