Systemic and regional hemodynamic changes associated with anterior hypothalamic lesions in conscious rats.

Systemic and regional hemodynamics were determined with the radioactive microsphere technique either in conscious "sham-lesioned" Wistar rats or after bilateral electrolytic lesions of the nuclei of the anterior hypothalamus. Both mean arterial pressure (111 +/- 4 vs 152 +/- 3 mm Hg) and heart rate (376 +/- 15 vs 504 +/- 12 beats/min) were significantly increased 2 hours after lesioning (p less than 0.001). Although cardiac output tended to increase, it did not attain statistical significance; therefore this form of neurogenic hypertension is characterized by increased total peripheral resistance. Regional hemodynamics were measured 2 hours after placement of the lesions: skeletal muscle flow increased, renal cutaneous and splanchnic flows decreased, and brain and myocardial flows were preserved. These hemodynamic alterations were associated with significant elevations in plasma norepinephrine and epinephrine levels, and behavioral changes characterized by hypermotility, aggressitivity, and irritability, which resembled those seen during fighting and exercise.