Effect of nitric oxide synthase inhibition on regional blood flow duringhyperthermia

摘要

The loss of compensatory splanchnic vasoconstriction during hyperthermia was assessed in rats after administration of either 0, 10, 30, or 100 mg/kg N-w-nitro-L-arginine methyl ester, L-NAME. Rectal temperature (T-re), heart rate (HR), mean arterial blood pressure (MAP), breathing frequency (BF), and renal, mesenteric and caudal blood flows (Q(R), Q(M) and Q(C)) were measured until irreversible cardiovascular collapse occurred. HR, MAP and BF increased as T-re rose to 42 degreesC. then fell as circulatory collapse occurred. As dose increased T-re at collapse decreased, Q(M) decreased until a T-re of 41.5-42 degreesC and then increased. Q(R) and Q(C) were unaffected by either hyperthermia or L-NAME. Inhibition of NO synthase did not prevent the circulatory collapse of heatstroke; the higher doses of L-NAME may have exacerbated the onset of circulatory failure.