The role of the anteromedial hypothalamus in Dahl hypertension.

Radiofrequency lesions were placed in the anteromedial hypothalamus in Dahl rats to investigate the role of this area in salt-induced hypertension. Lesions of the paraventricular and suprachiasmatic nuclei and intervening tissue (PVN-SCN lesions) prevented the rise in blood pressure (mmHg) in salt-sensitive (DS) rats fed a high-salt (8% NaCl) diet for 15 weeks (controls: 195 +/- 9, lesioned: 128 +/- 11, p less than 0.01). Similar lesions in salt-resistant (DR) rats did not alter long-term blood pressure (controls: 121 +/- 6 mmHg, lesioned: 131 +/- 5). Lesions sparing the PVN had no effect on blood pressure in DS rats, while lesions primarily confined to the PVN delayed the rise of blood pressure in DS fed a high salt diet. Round-the-clock determinations demonstrated that the blood pressure of DS rats with PVN-SCN lesions was reduced relative to controls at all times of the day throughout the study. No differences were observed between the angiotensin-induced drinking and plasma sodium concentrations of rats with PVN-SCN lesions and those of controls. Twenty-four hour mean heart rate was decreased by 10% in DS rats with PVN-SCN lesions. The anteromedial hypothalamus may participate in the initiation of Dahl hypertension.