[The pressor response induced by electrical stimulation of hypothalamic paraventricular nucleus in the cat]

The experiments were performed on 24 adult cats anesthetized with chloralose and urethane, paralyzed and artificially ventilated. Electrical stimulation of the hypothalamic paraventricular nucleus (PA) with a 12s train of 0.1-0.5 mA and 0.2ms square wave pulses at a frequency of 80 Hz induced a marked increase in arterial blood pressure (n = 19). The 22 points stimulated with maximum responses were clustered in the posterior dorsomedial part of the PA, among them 11 points were associated with an increase in heart rate and 7 a decrease. The remaining 4 points were associated with no change of heart rate, and situated in the anterior part of the PA. Electrolytic lesion of bilateral caudal half of the nucleus of solitary tract (NTS) had no significant effect on cardiovascular responses elicited from electric stimulation of the PA (n = 5). The results suggest that the PA is one of the important centers regulating cardiovascular activity; the NTS may not be involved in the PA pressor response.