Regional hemodynamic effects produced following application of L-glutamic acid to the ventral medullary surface of the cat.

The neuronal stimulant L-glutamic acid (GA) was applied to the ventral medullary surface and diastolic arterial blood pressure (DBP), heart rate (HR), renal and femoral arterial blood flow were measured in the chloralose-anesthetized cat. GA (1.0 M) increased DAP by 27 +/- 6.6 mmHg (P less than 0.05, n = 6), but heart rate was not affected (P greater than 0.05). Renal arterial resistance (RR) increased by 15 +/- 5.8% (P less than 0.05) and femoral resistance (FR) increased by 46 +/- 10% (P less than 0.05). The difference in the change in RR and FR was statistically significant (P less than 0.05). These effects were dose-dependent and could be blocked by prior intravenous administration of the alpha-blocker prazosin. These data indicate that neurons in the intermediate area of the ventromedullary surface may have a greater control over femoral flow than renal flow.