Attenuated arterial and venous constriction in conscious rats with streptozotocin-induced diabetes.
We examined if arterial or venous constriction is impaired in early diabetes. Dose-pressor and mean circulatory filling pressure (index of venous tone) response curves to noradrenaline and angiotensin II were constructed in four groups of conscious, instrumented, Wistar rats pretreated with streptozotocin (60 mg/kg i.v.) or vehicle at 2 weeks prior to the study. Rats with diabetes, relative to controls, had increased ED(50) (reduced potency) for the pressor (2.5-fold of control) and mean circulatory filling pressure (4.3-fold of control) response to noradrenaline, as well as reduced maximum pressor response (efficacy) to noradrenaline (diabetic, 74+/-8 mm Hg; control, 96+/-5 mm Hg). Diabetic rats also had reduced potency (ED(50), 5-fold of control) of the pressor response to angiotensin II; however, maximum pressor response and dose-mean circulatory filling pressure curve to angiotensin II were similar in both groups. Therefore, arterial and venous constrictions are impaired at an early phase of type I diabetes.
Cheng
Xing
X
Department of Pharmacology and Therapeutics, Faculty of Medicine, The University of British Columbia, Vancouver, Canada.
Leung
Susan W S
SW
Lim
Su L
SL
Pang
Catharine C Y
CC
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000503:physiopathology*; D001794:Blood Pressure / Q000187:drug effects; D003243:Consciousness; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014680:Veins / Q000187:drug effects / Q000503:physiopathology*
D000804:Angiotensin II; D009638:Norepinephrine