The effects of hypertension and diabetes mellitus on the vascular reactivity of resistance arteries.
We have studied the effects of both hypertension and streptozotocin-induced diabetes mellitus on alpha 1-adrenoceptor mediated vasoconstriction, endothelium-dependent and endothelium-independent vasodilation. The experiments were performed in perfused mesenteric vascular bed preparations taken from age-matched SHR, WKY, diabetic SHR and diabetic WKY. For the alpha 1-adrenoceptor agonist methoxamine, the mesenteric preparations from SHR and diabetic SHR yielded significantly (p < 0.05) stronger maximal responses than preparations taken from WKY and diabetic WKY, respectively. The diabetic state significantly (p < 0.05) decreased the responsiveness to methoxamine in arteries from SHR and WKY. Hypertension does not significantly change the concentration response-curves for (acetyl-beta) methacholine, histamine, adenosine diphosphate and sodium-nitroprusside. However, the sensitivity to endothelium-dependent vasodilation decreased in preparations from diabetic animals (< 0.05). It is concluded that mesenteric resistance arteries from SHR and diabetic SHR are more reactive to alpha 1-adrenoceptor stimulation, whereas diabetes reduces the responsiveness to methoxamine in WKY and SHR. Hypertension does not affect the endothelium-dependent relaxation in mesenteric arteries. However, diabetes decreases the sensitivity to endothelium-dependent relaxation without altering the sensitivity to sodium-nitroprusside. These findings are indicative of a diabetes-induced endothelial dysfunction in mesenteric resistance arteries. In preparations from diabetic hypertensive rats the reduced response to methoxamine and the endothelial dysfunction seem to run parallel.
Hendriks
M G
MG
Department of Pharmacotherapy, University of Amsterdam, The Netherlands.
Kam
K L
KL
Pijl
A J
AJ
Pfaffendorf
M
M
van Zwieten
P A
PA
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000502:physiology; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008638:Mesenteric Arteries / Q000503:physiopathology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014655:Vascular Resistance / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology