Potentiation of the cardiovascular effects of nicardipine by enflurane anesthesia in canine blood-perfused heart preparations.

The cardiovascular interaction between nicardipine (N) and enflurae (E) was examined with blood perfused isolated paplillary muscle preparations (PMP) and sinoatrial node preparations (SNP). Blood flow to these preparations was supplied by either conscious or 1.7% E-anesthetized-donor dogs. N was administered continuously at a rate of 2.0 microg.kg(-1).min(-1) into the donor dogs for 60 min. Measurements were as follows: mean arterial blood pressure (MAP), heart rate (DHR), PQ interval (PQ) in the electrocardiogram, developed tension (DT) in PMP, sinoatrial rate (SAR) in SNP and blood flow (BF) to PMP and SNP. There were no significant differences in PQ, SAR and BF between two groups. However, N further decreased MAP, DHR and DT that were already decreased by E significantly. The authors conclude that the cardiovascular interaction between N and E was generally additive but that concerning negative inotropism was synergistic.