EFFECTS OF HYPERINSULINEMIA ON THE REGULATION OF REGIONAL BLOOD-FLOW AND BLOOD-PRESSURE IN ANESTHETIZED DOGS HEMODYNAMIC ROLE OF NITRIC-OXIDE

The purpose of this study was to investigate whether acute hyperinsuli nemia induces selective hemodynamic effects in the mesenteric, renal, and iliac vascular beds, and to determine whether nitric oxide (NO) pl ays a role in the regulation of blood now and mean arterial pressure ( MAP) during acute hyperinsulinism. In eight anesthetized dogs (Group A ), the response to a hyperinsulinemic test was determined before and a fter NO inhibition, with L-nitro-arginine methyl esther (L-NAME), duri ng the last 45 min of the experiment. In seven dogs (Group B), NO inhi bition was induced before and maintained throughout hyperinsulinemia. In Group A, the hyperinsulinemic test did not alter MAP, but induced a significant reduction in both renal and mesenteric blood now without a significant change in iliac blood now. In contrast, the administrati on of L-NAME in Group B was followed by a significant decrease in mese nteric, renal, and iliac blood now, but mean arterial pressure remaine d unchanged. In this group, hyperinsulinemia instituted after the bloc kade of NO was followed by a significant elevation in blood pressure l evels, concomitant with reductions in blood now to the three vascular beds. In summary, acute hyperinsulinemia induced a redistribution of b lood supply, which preserves skeletal muscle irrigation while reducing blood now to the kidney. Nitric oxide participates in this redistribu tion because L-NAME infusion abolishes the compensatory influence on s keletal muscle blood now. Am J Hypertens 1998;11:1232-1238 (C) 1998 Am erican Journal of Hypertension, Ltd.