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      Size Dependence of Functional Alterations in Mesenteric Arteries from the Aldosterone-Salt Hypertensive Rat


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          We tested the hypothesis that an elevated potassium-42 (<sup>42</sup>K<sup>+</sup>) efflux (highly dependent on Ca<sup>2+</sup>) and an increase in the sensitivity of contraction and <sup>42</sup>K<sup>+</sup> efflux to norepinephrine (NE) in conduit arteries of aldosterone-salt hypertensive rats (AHR) exended to smaller, distributing arteries. Functional endpoints were compared in two sizes of arteries from the mesenteric bed: second-order branches of the superior mesenteric artery (SMA branches) and the SMA. Contraction and free cytosolic Ca<sup>2+</sup> concentration ([Ca<sup>2+</sup>]<sub>c</sub>; fura-2 microfluorometry) were measured simultaneously and <sup>42</sup>K<sup>+</sup> efflux was measured separately in SMA branches. Contraction and <sup>42</sup>K<sup>+</sup> efflux were measured separately in SMA. Basal tone, [Ca<sup>2+</sup>]<sub>c</sub>, and <sup>42</sup>K<sup>+</sup> efflux were similar in SMA branches from AHR and control-salt rats (CSR). However, basal <sup>42</sup>K<sup>+</sup> efflux was elevated in SMA from AHR compared to CSR. The sensitivity of the contractile, [Ca<sup>2+</sup>]<sub>c</sub>, and <sup>42</sup>K<sup>+</sup> efflux responses to NE was similar in SMA branches. In contrast, the sensitivity of the contractile and <sup>42</sup>K<sup>+</sup> efflux responses to NE was enhanced in SMA from AHR compared to CSR. Inhibiton of endothelium-derived vasoactive substances by pretreatment with N<sub>ω</sub>-nitro- L-arginine methyl ester and indomethacin significantly shifted the NE concentration-response relationships to the left for contraction, [Ca<sup>2+</sup>]<sub>c</sub>, and <sup>42</sup>K<sup>+</sup> efflux in both SMA branches and SMA from CSR. A similar shift to the left was observed in AHR for contraction but not consistently for [Ca<sup>2+</sup>]<sub>c</sub> and <sup>42</sup>K<sup>+</sup> efflux. We conclude that SMA branches from AHR demonstrate neither the elevated basal <sup>42</sup>K<sup>+</sup> efflux, nor the NE supersensitivity exhibited by SMA. Endothelial function was not impaired both in SMA and SMA branches.

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          α1- and α2-adrenoceptor agonist-induced contraction in rat mesenteric artery upon removal of endothelium

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            Involvement of α-adrenoceptors in the endothelium-dependent depression of noradrenaline-induced contraction in rat aorta


              Author and article information

              J Vasc Res
              Journal of Vascular Research
              S. Karger AG
              October 1999
              28 October 1999
              : 36
              : 5
              : 404-414
              Department of Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Mo., USA
              25680 J Vasc Res 1999;36:404–414
              © 1999 S. Karger AG, Basel

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              Page count
              Figures: 5, Tables: 4, References: 31, Pages: 11
              Research Paper


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