Actions of neurotransmitters and peptides on longitudinal and circular muscle of the rat portal vein

Mathison, Ron

doi:10.1111/j.2042-7158.1983.tb04259.x

Cited by 13 publications

(8 citation statements)

References 11 publications

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“…The circular preparation of rat portal vein did not show spontaneous mechanical activity, as reported previously (Cohen and Weily, 1977 ;Mathison, 1983 ;Bratveit et al, 1987). Responses to agonists has also been reported to be different between longitudinal and circular muscle of rat portal vein (Mathison, 1983 ;Bratveit et al, 1987 ;Rydningen et al, 1987 ;see Sutter, 1990).…”

Section: Discussionsupporting

confidence: 82%

Ca2+-Sensitivity of Portal Vein Circular Muscle from Normotensive and Hypertensive Rats.

Shimamura

Zou

Matsuda

et al. 1998

J. Smooth Muscle Res.

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Contractile sensitivity to Ca2+ was studied in rat portal vein circular muscle isolated from normotensive Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). There was no difference in resting membrane potential between WKY and SHRSP. Elevation of extracellular K+ concentration induced similar increase in tension in preparations from WKY and SHRSP. High K+-depolarized preparation developed tension increase when extracellular Ca2+ concentration was increased. The sensitivity to extracel lular Ca2+ was similar in preparations from WKY and SHRSP. Permeabilized preparation contracted when free Ca2+ concentration was increased. Sensitivity of permeabilized preparation to Ca2+ was similar in preparations from WKY and SHRSP. These results indicate that regulation of contraction by Ca2+ was similar between WKY and SHRSP. Since there was no change in high K-induced contraction in intact preparations or Cainduced contraction in permeabilized preparations, there seemed to be no difference in influx via voltage-dependent channels in portal vein circular muscle from WKY and SHRSP.

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Section: Discussionsupporting

confidence: 82%

Ca2+-Sensitivity of Portal Vein Circular Muscle from Normotensive and Hypertensive Rats.

Shimamura

Zou

Matsuda

et al. 1998

J. Smooth Muscle Res.

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“…The circular preparation did not show spontaneous rhythmic mechanical activity as has been reported previously [16,23]. There was a remarkable difference from previous findings in longitudinal preparations that show rhythmic contractions of low frequency and high amplitude initiated by rhythmic bursts of action potentials [1,12,22,25].…”

Section: Discussionsupporting

confidence: 48%

Role of nitric oxide in the contraction of circular muscle in the rat portal vein

Shimamura

Zou²,

Matsuda³

et al. 2000

Pflugers Arch - Eur J Physiol

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The role of nitric oxide in the electrical and mechanical activities of the rat portal vein was examined in circular muscle preparations with intact endothelium that were isolated from the longitudinal muscle layer. In contrast to the longitudinal muscle preparation, the circular muscle preparation did not show spontaneous phasic contraction. Inhibition of nitric oxide synthesis by Nomega-nitro-L-arginine (L-NNA) induced a tonic contraction. The contraction was inhibited by L-arginine, sodium nitroprusside or nifedipine. L-NNA did not induce contraction in endothelium-damaged preparations. The membrane potential of smooth muscle cells recorded in endothelium-intact preparations showed sporadic action potentials. L-NNA increased the frequency of action potentials without changing the resting membrane potential. The action potentials were inhibited by nifedipine. In the presence of L-NNA, sodium nitroprusside decreased the frequency of the action potentials without changing the resting membrane potential. These results indicated that contraction of rat portal vein circular muscles is inhibited tonically by nitric oxide, at least partly through inhibition of electrical activity.

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“…The weak contractile effects produced by histamine and carbachol do not rule out the possibility that these agents may participate in the regulation of the liver circulation, since they may act as vasodilators, an aspect which was not examined in the present study. In this respect, branches of the portal vein seem to differ from both the longitudinal and circular muscles of the rat portal vein, which responded with a significant contraction after acetylcholine application in vitro (Mathison 1983). The higher NA sensitivity of the portal veins compared with the hepatic arteries was not attributable to differences in the neuronal uptake mechanism, since the potency difference was present also after hepatic hilar denervation or exposure to cocaine.…”

Section: Discussionmentioning

confidence: 84%

Contractile effects of various vasoactive agents in small rat portal veins and hepatic arteries and the influence of sympathetic denervation on the noradrenaline response

Högestätt

Hammarström

Andersson

et al. 1986

Acta Physiologica Scandinavica

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Contractile responses were studied in isolated tubal segments of branches of the rat portal vein (luminal diameter approximately 300 microns) and hepatic artery (luminal diameter approximately 200 microns). Portal veins were approximately three times more sensitive to noradrenaline (NA) than hepatic arteries. 5-hydroxytryptamine contracted hepatic arteries concentration-dependently, whereas it produced only weak and inconsistent contractions in portal veins. Vasopressin effectively contracted hepatic arteries, whereas it had no effect on portal veins. Both vessel types responded to prostaglandin F2 alpha with contractions, although the drug potency was relatively low (EC50 greater than 10(-5) mol l-1). Histamine and carbachol failed to induce (hepatic arteries) or caused only weak (portal veins) contractions. Microsurgical hepatic hilar denervation reduced the catecholamine content of the parenchyma to less than or equal to 25% of controls. In both portal veins and hepatic arteries, the denervation procedure increased the NA sensitivity by factors of 3.1 and 2.0, respectively. In non-denervated livers, cocaine produced a similar increase of the NA sensitivity, whereas the drug had no significant effect in vessels from denervated animals. Thus, there was a marked difference between rat portal veins and hepatic arteries in their responsiveness to several contractile agents. Furthermore, the results of the present study indicate that the adrenergic nerves in both vessel types can be adequately removed by the microsurgical denervation procedure used.

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Actions of neurotransmitters and peptides on longitudinal and circular muscle of the rat portal vein

Cited by 13 publications

References 11 publications

Ca2+-Sensitivity of Portal Vein Circular Muscle from Normotensive and Hypertensive Rats.

Ca2+-Sensitivity of Portal Vein Circular Muscle from Normotensive and Hypertensive Rats.

Role of nitric oxide in the contraction of circular muscle in the rat portal vein

Contractile effects of various vasoactive agents in small rat portal veins and hepatic arteries and the influence of sympathetic denervation on the noradrenaline response

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