AJP - Heart and Circulatory Physiology, Vol 256, Issue 4 1134-H1138, Copyright © 1989 by American Physiological Society

ARTICLES

Vascular sensitivity and reactivity to norepinephrine in diabetes mellitus

J. J. Friedman
Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis 46223.

Vascular sensitivity (VS) and reactivity (VR) of hindquarters, totally isolated from rats made diabetic with 45 mg/kg of streptozotocin (STZ), were determined at 1, 2, 4, 8, and 12 wk post-STZ. Age-matched controls received saline injections and were followed for comparable periods. The hindquarters were perfused at constant flow (8-10 ml/min) with a Tyrode-perfluorocarbon (FC-43)albumin-alpha-globulin solution gassed with 95% O2-5% CO2. Tissues were continuously weighed and venous pressure adjusted to maintain an isogravimetric condition. VS and VR were determined from norepinephrine (NE) dose-response curves generated by infusing stock NE (1 mg/ml) at progressively increasing rates (0.004-0.025 ml/min) into a constant tissue perfusion rate (8-10 ml/min) for sufficient time to reach a plateau (2-3 min). Delivered doses ranged from 0.4 to 2.5 micrograms/ml. VR was established as the perfusion pressure reached in response to 2.5 micrograms/ml NE (Pmax). VS was defined as the delivered NE dose that increased perfusion pressure to 50% of Pmax (ED50). VS increased slightly but significantly (P less than 0.01) by 1 wk post-STZ and remained above control throughout the 12-wk post-STZ period. VR also increased significantly (P less than 0.05) by 1 wk post-STZ and remained above control throughout the 12-wk post-STZ period.

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