Role of nitric oxide in systemic vasopressin-induced hypothermia

1 Faculdade de Odontologia de Ribeirão Preto, 2 Escola de Enfermagem de Ribeirão Preto, and 3 Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, 14040-904 Ribeirão Preto, São Paulo, Brazil It has been reported that arginine vasopressin (AVP) plays a thermoregulatory action, but very little is known about the mechanisms involved. In the present study, we tested the hypothesis that nitric oxide (NO) plays a role in systemic AVP-induced hypothermia. Rectal temperature was measured before and after AVP, AVP blocker, or N G -nitro- L -arginine methyl ester ( L -NAME; NO synthase inhibitor) injection. Control animals received saline injections of the same volume. The basal body temperature (T b ) measured in control animals was 36.53 ± 0.08°C. We observed a significant ( P