Area postrema stimulation induces differential renal hemodynamics with two anesthetics

The effect of area postrema stimulation (APS) on blood pressure, renal blood flow (RBF), and renal vascular resistance was compared in urethan-anesthetized and pentobarbital sodium-anesthetized Sprague-Dawley rats. Mean arterial pressure (MAP) increased in a frequency-dependent manner during APS in both urethan- and pentobarbital-anesthetized rats. Although no significant differences occurred in the maximum percent change in MAP between groups, marked differences occurred in RBF and calculated renal vascular resistance (RVR) changes. In urethan-anesthetized rats, RBF and MAP increased during APS, but RVR did not change. In contrast, APS significantly decreased RBF (-26.5 +/- 1.9%) while increasing RVR (+99.4 +/- 11.4%) in pentobarbital-anesthetized rats. The increase in RVR in the pentobarbital-anesthetized group during APS was eliminated by prior ganglionic blockade. It was concluded that the anesthetic agent employed can significantly alter the degree to which APS can activate renal vasomotion in the rat.