Effects of adrenoceptor agonists and antagonists on smooth muscle cells and neuromuscular transmission in the guinea‐pig renal artery and vein

Makita, Yuji

doi:10.1111/j.1476-5381.1983.tb10057.x

Cited by 23 publications

(15 citation statements)

References 29 publications

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“…Thus, on the basis of growing evidence demonstrating the presence ofa2-adrenoceptors in venous smooth muscle (Makita, 1983;Suzuki, 1984;Cheung, 1985;Docherty & Hyland, 1985), it is reasonable to assume that the results obtained in the present study indicate that both a,-and M2-adrenoceptors are present in the arterial circulation of the cat hindquarters, while there was an exclusive, or at least predominant, X2-adrenoceptor population in the venous circulation. These findings are consistent with others (De Mey & Vanhoutte, 1981; Vanhoutte, 1982;Glusa & Markwardt, 1983) which indicate that venous smooth muscle contains a greater proportion of o2-adrenoceptors than does arterial smooth muscle, although all previous evidence was based on in vitro data.…”

Section: Discussionsupporting

confidence: 56%

Postjunctional α₂‐adrenoceptors mediate venoconstriction in the hindquarters circulation of anaesthetized cats

Bentley

Widdop

1987

British J Pharmacology

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1 A study was made of the subtypes of postjunctional a-adrenoceptors which mediate arterial and venous constriction in the hindquarters circulation of anaesthetized cats, as measured by changes in perfusion pressure and vena cava blood flow, respectively. 2 It was found that, while noradrenaline caused constriction in both the arterial and venous compartments, methoxamine caused only arterial constriction. Clonidine and B-HT 920 also caused arterial and venous constriction although autodesensitization to both drugs occurred. 3 The ability of either prazosin or yohimbine to antagonize the constrictor effects of noradrenaline was also examined. It was found that the combination of both antagonist drugs abolished both the arterial and venous constrictor effects of noradrenaline. However, there was a greater prazosinresistant response to noradrenaline in the venous compartment as compared with the arterial effects of noradrenaline. Yohimbine caused approximately equal reductions in the effect of noradrenaline in both arteries and veins, which was greater than that observed with prazosin. 4 These results suggest that, in the cat hindquarters, both a,-and a2-adrenoceptors are present in the arterial circulation, whereas there are mainly a2-adrenoceptors in the venous circulation.

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Section: Discussionsupporting

confidence: 56%

Postjunctional α₂‐adrenoceptors mediate venoconstriction in the hindquarters circulation of anaesthetized cats

Bentley

Widdop

1987

British J Pharmacology

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“…There is also evidence that a2 receptors mediate part of the mechanical (Vanhoutte et al 1981) and electrical (Makita, 1983) response ofveins to noradrenaline.…”

Section: Discussionmentioning

confidence: 99%

“…Adrenoceptors of the smooth muscle have been subdivided into al receptors; a2 receptors with pharmacological properties of the prejunctional adrenoceptor (Langer, 1977;Vanhoutte et al 1981;Ruffolo, Waddell & Yaden, 1981, 1982Makita, 1983); and also intrajunctional adrenoceptors which are present at the neuromuscular junction (Hirst & Neild, 1981). Contractions evoked by exogenous noradrenaline were blocked to varying degrees by a, and a2 adrenoceptor blocking agents, while miniature e.j.p.s (m.e.j.p.s) and e.j.p.s were less readily blocked by these agents (Holman & Surprenant, 1980;Hirst & Neild, 1981;Suzuki & Kuriyama, 1980;Kajiwara et al 1981;Kuriyama & Makita, 1982.…”

Section: Introductionmentioning

confidence: 99%

Roles of extrajunctional receptors in the response of guinea‐pig mesenteric and rat tail arteries to adrenergic nerves.

Itoh¹,

Kitamura²,

Kuriyama³

1983

The Journal of Physiology

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SUMMARY1. Studies of the electrical response of isolated guinea-pig mesenteric and rat tail arteries to perivascular nerve stimulation were made by micro-electrodes inserted from the outer surface of the vessels.2. Membrane potential of both arteries was -68 to -69 mV and usually stable, though with occasional miniature excitatory junction potentials (m.e.j.p.s).3. Perivascular nerve stimulation produced excitatory junction potentials (e.j.p.s) which usually increased in size with repetitive stimulation, particularly in the mesenteric artery, but rarely triggered a spike or other regenerative response. Phentolamine and yohimbine in low concentrations increased the size of the e.j.p.s in both arteries, and increased the mechanical response of the mesenteric artery, probably by blocking prejunctional a2 receptors which depress release ofnoradrenaline by the nerves; they reduced the mechanical response of the tail artery, probably by blocking a2 receptors of the smooth muscle. Prazosin in low concentration had no effect on the e.j.p.s but inhibited contraction in both arteries, probably by blocking a, receptors of the smooth muscle.4. In the tail artery, but not the mesenteric artery, e.j.p.s produced by repetitive perivascular nerve stimulation were followed by a slow depolarization reaching a maximum at about 20s and then decaying over 1-3 min; it did not reach the threshold for contraction, assessed by K depolarization. Yohimbine reduced the size and duration of the slow depolarization.5. High concentrations of noradrenaline (10-5 M) caused depolarization and contraction of the mesenteric artery, both of which were blocked by prazosin and little affected by yohimbine. In the tail artery, yohimbine did but prazosin did not block the depolarization produced by any concentration of noradrenaline, although yohimbine was almost as effective as prazosin in blocking the contraction produced by low concentrations of noradrenaline.6. Extrajunctional adrenoceptors in the mesenteric artery therefore included high sensitivity types of a, receptor, and in the tail artery high sensitivity types of a, and a2 receptor.

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“…In some vascular beds, differences in resting membrane potentials of the smooth muscles suggest that veins, with potentials less negative by 10-15 mV, are closer to threshold for contraction and thus may require less depolarization than is required for arterial contraction (Suzuki, 1981;Kuriyama & Suzuki, 1981;Itoh et al 1983;Kuriyama & Makita, 1983Makita, 1983;Morgan, 1983). This does not appear to be the case in the present study, as the difference in average membrane potential was not more than 2-8 mV.…”

Section: Discussionmentioning

confidence: 99%

Comparison of the frequency dependence of venous and arterial responses to sympathetic nerve stimulation in guinea‐pigs.

Hottenstein

Kreulen

1987

The Journal of Physiology

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SUMMARY1. Intracellular potentials and measurements of contractions were recorded in adjacent veins and arteries in the colonic mesentery of the guinea-pig in vitro during stimulation of post-ganglionic nerve trunks.2. Repetitive stimulation (0'S5-Hz) of lumbar colonic nerve trunks produced frequency-dependent slow depolarizations in all venous and in 92 % ofarterial smooth muscle cells. Excitatory junction potentials were observed for each nerve shock in arteries, but not in veins.3. Low-frequency stimulations produced slow depolarizations of greater amplitude and longer duration in veins than in arteries. The frequencies at which half-maximal depolarizations and contractions occurred were always lower for veins than for arteries.4. The az-adrenergic antagonist prazosin (5 x 10-7 M) reduced the mean arterial slow depolarizations by 82 % and reduced mean venous slow depolarizations by 58 % for 5 Hz stimulations. Arterial contractions were completely inhibited by prazosin but venous contractions were incompletely reduced in a frequency-dependent manner.5. These findings suggest that functional differences in activation between mesenteric veins and arteries during sympathetic stimulation are a result of differences in neuromuscular transmission.

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Effects of adrenoceptor agonists and antagonists on smooth muscle cells and neuromuscular transmission in the guinea‐pig renal artery and vein

Cited by 23 publications

References 29 publications

Postjunctional α₂‐adrenoceptors mediate venoconstriction in the hindquarters circulation of anaesthetized cats

Postjunctional α₂‐adrenoceptors mediate venoconstriction in the hindquarters circulation of anaesthetized cats

Roles of extrajunctional receptors in the response of guinea‐pig mesenteric and rat tail arteries to adrenergic nerves.

Comparison of the frequency dependence of venous and arterial responses to sympathetic nerve stimulation in guinea‐pigs.

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Effects of adrenoceptor agonists and antagonists on smooth muscle cells and neuromuscular transmission in the guinea‐pig renal artery and vein

Cited by 23 publications

References 29 publications

Postjunctional α2‐adrenoceptors mediate venoconstriction in the hindquarters circulation of anaesthetized cats

Postjunctional α2‐adrenoceptors mediate venoconstriction in the hindquarters circulation of anaesthetized cats

Roles of extrajunctional receptors in the response of guinea‐pig mesenteric and rat tail arteries to adrenergic nerves.

Comparison of the frequency dependence of venous and arterial responses to sympathetic nerve stimulation in guinea‐pigs.

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Postjunctional α₂‐adrenoceptors mediate venoconstriction in the hindquarters circulation of anaesthetized cats

Postjunctional α₂‐adrenoceptors mediate venoconstriction in the hindquarters circulation of anaesthetized cats