Cardiac effects of oxytocin: Is there a role for this peptide in cardiovascular homeostasis?

Oxytocin is well known for its role in reproduction. However, evidence has emerged suggesting a role in cardiovascular and hydroelectrolytic homeostasis. Although its renal effects have been characterized, the cardiac ones have not been much studied. Therefore, we aimed to investigate the cardiac effects of oxytocin both in vivo and in vitro. In unanesthetized rats (n=6) intravenous oxytocin (1 mu g) decreased dP/dt(max) by 15% (P < 0.05) and heart rate by 20% (P < 0.001), at the first minute after injection. dP/dt(max) was still lower in OT-treated rats than in controls (n=8) after 15 min (P < 0.05), while heart rate returned to control values after 5 min. In isolated hearts, oxytocin was able to promote negative inotropic and chronotropic effects. Perfusion with 10(-5), 10(-6) and 10(-7)M oxytocin resulted in approximately 60% (P < 0.01), 25% (P < 0.01) and 10% (P < 0.05) reduction of left ventricle developed pressure, without effect in lower concentrations (10(-10) to 10(-8) M). Also, dP/dt(max), was reduced by 45 and 20% (10(-5) e 10(-6) M; p < 0.01), while diastolic pressure raised and heart rate fell only with 10(-5)M oxytocin (P < 0.05). Intravenous oxytocin (1 mu g; n=6) increased arterial pressure by 22% at the first minute (+23 +/- 3 min Hg; P < 0.001), returning to control value thereafter. Thus, oxytocin is able to promote directly negative inotropic and chronotropic effects, but its in vivo effect also involves a reflex mechanism, originated from its pressor effect. (c) 2005 Elsevier B.V. All rights reserved

Analysis and estimative of schistosomiasis prevalence for the state of Minas Gerais, Brazil, using multiple regression with social and environmental spatial data

The aim of this work is to establish a relationship between schistosomiasis prevalence and social-environmental variables, in the state of Minas Gerais, Brazil, through multiple linear regression. The final regression model was established, after a variables selection phase, with a set of spatial variables which contains the summer minimum temperature, human development index, and vegetation type variables. Based on this model, a schistosomiasis risk map was built for Minas Gerai