1. Mesenteric small artery changes after vasoconstrictor infusion in young rats.
- Author
-
Boonen HC, Daemen MJ, Eerdmans PH, Fazzi GE, van Kleef EM, Schiffers PM, and De Mey JG
- Subjects
- Animals, Blood Pressure drug effects, Endothelium, Vascular physiology, Hemodynamics drug effects, Male, Mesenteric Arteries physiology, Muscle Contraction drug effects, Muscle Contraction physiology, Muscle Relaxation drug effects, Muscle Relaxation physiology, Muscle, Smooth, Vascular drug effects, Muscle, Smooth, Vascular physiology, Phenylephrine pharmacology, Rats, Rats, Inbred SHR, Rats, Inbred WKY, Vascular Resistance drug effects, Angiotensin II pharmacology, Hypertension physiopathology, Mesenteric Arteries drug effects, Receptors, Adrenergic, alpha drug effects, Vasoconstrictor Agents pharmacology
- Abstract
We evaluated whether chronic alpha 1-adrenergic stimulation, angiotensin II (AII), or increased blood pressure (BP) alters resistance arterial structure and function. Structural parameters and wall tension were recorded in mesenteric small arteries (MrA) isolated from 6-week-old normotensive Wistar Kyoto rats that had been infused for 4 days with saline (WKY), 2 mg/kg/day phenylephrine (WKY + PHE), or 0.3 mg/kg/day AII (WKY + AII) and from saline-infused spontaneously hypertensive rats (SHR). During the experimental period, systolic BP (SBP) did not change in WKY but increased in WKY + PHE, WKY + AII, and SHR. Relative cardiac mass did not differ between SHR and WKY, but was increased in WKY + PHE and WKY + AII. Stiffness and optimal lumen diameter of MrA did not differ between WKY and SHR and were not altered in WKY + PHE or WKY + AII. Maximal contractile responses and sensitivities for vasconstrictors and calcium in vessels of WKY + AII and SHR did not differ from those in WKY. In vessels of WKY + PHE, maximal responses to vasoconstrictors and sensitivities for norepinephrine (NE) and PHE were reduced. Relaxing responses to isoproterenol (ISO) and Na-nitroprusside did not differ between SHR and WKY and were not altered in WKY + PHE and WKY + AII. Those to acetylcholine (ACh) were reduced in WKY + PHE. Media cross-sectional area and media thickness were significantly larger in WKY + AII and SHR as compared with WKY but were not altered in WKY + PHE. These data indicate that in young rats AII leads to small artery hypertrophy and that neither increased BP or increased vasconstriction appear to be involved therein. Chronic alpha 1-adrenergic stimulation, on the other hand, did not modify small artery structure but resulted in nonselective reduction of arterial smooth muscle contractile reactivity.
- Published
- 1993
- Full Text
- View/download PDF