Influence of alpha-receptor blocking agents upon metabolic activity in nuclei involved in central control of blood pressure.

The energy metabolism of the central nervous structures involved in the regulation of blood pressure was examined by means of the autoradiographic 2-deoxy-D-[14C]glucose method in normal, awake rats during hypotension induced by the alpha-adrenergic blockers, phentolamine, phenoxybenzamine, and yohimbine. Administration of these alpha-blockers produced a dose-dependent increase of glucose consumption in the medial nucleus of the solitary tract (NTSm), the dorsal motor nucleus of the vagus (DMX), the nucleus ambiguus (NA), and the paraventricular (PAVH) and supraoptic (SO) hypothalamic nuclei. However, in the external cuneate nucleus and in the paramedian reticular nucleus there was a decrease in glucose utilization. These changes appear to be at least partly due to the hypotension produced by the drugs in addition to their central effects; when the hypotension was prevented by administration of the plasma expander, dextran, in phenoxybenzamine-treated rats, the effects were less than those observed in animals with hypotension not limited by dextran infusion.