Membrane electrical mechanism of basilar artery constriction and pial artery dilation by norepinephrine.

Harder, David R.; Abel, P W; Hermsmeyer, Kent

doi:10.1161/01.res.49.6.1237

Cited by 39 publications

(21 citation statements)

References 19 publications

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“…The choice of small mesentery artery for these experiments was fortunate in that the threshold for the opening of appreciable numbers of potential-sensitive calcium channels was considerably positive, 15 mV or so, to the resting membrane potential, so that there was a clear separation of the membrane potentials associated with equally sized contractions to high [K+]o and to noradrenaline. In some other arteries the threshold [K+]0 for contraction is less so that this separation is less or non-existent and, furthermore, the opening of receptor-operated channels has been reported to produce a large depolarization (Harder et al 1981;Trapani et al 1981). This would bring into play the opening of potential-sensitive calcium channels so that in these arteries three types of calcium mechanism at least would seem to be involved in tension generation to noradrenaline.…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of action of noradrenaline and carbachol on smooth muscle of guinea‐pig anterior mesenteric artery.

Bolton¹,

Lang²,

Takewaki³

1984

The Journal of Physiology

232

132

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SUMMARY1. Membrane potential was recorded by micro-electrode in segments of small (200-500 jsm o.d.) mesenteric arteries of guinea-pig. Isotonic shortening was recorded in helical strips cut from these arteries.2. Raising the external potassium concentration, [K+]0, caused shortening and substantial depolarization. The threshold for contraction was about 30 mm which corresponded to a membrane potential of about -45 mV. Since high-potassium contractions were abolished in calcium-free solution it was suggested that they occur due to potential-sensitive calcium channels opening positive to about -45 mV.3. Noradrenaline weakly depolarized the muscle and produced contractions resistant to calcium-free conditions. It was suggested that noradrenaline contractions are mainly caused by mechanisms other than the opening of potential-sensitive calcium channels, namely entry of calcium via other channels and release of stored calcium.4. Carbachol had no effect on basal tension but inhibited shortening by noradrenaline or by raising [K+]0. The inhibitory effect of carbachol on tension under various conditions was associated with hyperpolarization or depolarization in a range negative to -45 mV, or no effect on potential, so that modulation of the number of open potential-sensitive calcium channels could not be evoked to explain its relaxant action.5. Removal or destruction of the endothelium by rubbing or by distilled water perfusion left tension responses to noradrenaline or raised [K+]. essentially unchanged. However, the inhibitory effect of carbachol on tension was attenuated and hyperpolarization of the resting artery was converted to a depolarization. 6. It was concluded that carbachol has both a strong inhibitory and a weak excitatory effect on these vascular smooth muscle cells. Membrane potential changes are not essential to its inhibitory action but may, by closing potential-sensitive calcium channels, sometimes reinforce it. Hyperpolarization by carbachol may be caused by a factor released by the action of carbachol on endothelial cells: in its absence carbachol may weakly depolarize but this alone is normally insufficient to generate tension.

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Section: Discussionmentioning

confidence: 99%

Mechanisms of action of noradrenaline and carbachol on smooth muscle of guinea‐pig anterior mesenteric artery.

Bolton¹,

Lang²,

Takewaki³

1984

The Journal of Physiology

232

132

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“…However, in various species it has been found that the cerebral arteries, in contrast to those of the periphery, are contracted weakly by noradrenaline (NA) in comparison to other agonists such as 5-hydroxytryptamine (5-HT), histamine and KCl (Nielsen & Owman, 1971;Toda & Fujita, 1973;Duckles & Bevan, 1976;Harder et al, 1981;Skarby et al, 1983;Usui et al, 1985;Tsukahara et al, 1986).…”

Section: Introductionmentioning

confidence: 99%

Pharmacological characterization of postjunctional α‐adrenoceptors in cerebral arteries from the sheep

Gaw

Wadsworth

1989

British J Pharmacology

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1The responsiveness to noradrenaline was characterized in cerebral arteries from the sheep, since this species was large enough to permit a comparison of arteries from different parts of the cerebral vasculature. 2 Noradrenaline caused contraction of the basilar artery, middle cerebral artery and small pial arteries by stimulation of a,-adrenoceptors. 5 The noradrenaline contraction, relative to the 5-HT contraction, was not affected by removal of the endothelium in either the sheep basilar or middle cerebral artery. 6 The results showed a variation within the sheep cerebral vasculature in the response to noradrenaline which cannot be explained by regional differences in x-adrenoceptor subtypes, noradrenaline uptake mechanisms or endothelial function.

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“…The researchers found a relationship between the size of the membrane potential of the VSMC layer and the muscle tone. Harder et al (1981) showed that the membrane potential of small mesenteric vessels in SHR rats (spontaneously hypertensive rat) is significantly different from that observed in normotensive WKY rats (WKY-WistarKyoto rat), but only during in vivo studies. However, in vitro no differences were observed.…”

Section: Discussionmentioning

confidence: 95%

“…This resulted in changes in the blood vessel diameter affecting the regulation of blood pressure (Nelson and Quayle 1995). The importance of membrane potential increase in VSMC (vascular smooth muscle cell) in the pathogenesis of hypertension has been demonstrated by Harder et al (1981). The researchers found a relationship between the size of the membrane potential of the VSMC layer and the muscle tone.…”

Section: Discussionmentioning

confidence: 99%

“…The biophysical properties of blood vessels are determined by the mutual quantity ratio of these three elements together and the ratio of the vessel wall thickness to the internal radius. The wall of larger arteries is characterized by a low ratio of wall thickness to the internal radius (on average 1 : 6), (Harder et al 1981). It is dominated by elastic fibres that provide it with considerable tensibility.…”

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confidence: 99%

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Myoelectric activity of the muscular layer of the abdominal aorta in pigs in vivo

et al. 2012

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The study was conducted on 5 pigs weighing 20-30 kg. Bipolar electrodes were surgically implanted into the muscular layer of the vascular smooth muscle cell of the abdominal aorta just below the renal arteries. Myoelectric activity characterized by the appearance of changes of membrane potential was found. Changes of potential could be divided according to the amplitude, duration and frequency into first-, second-and third-order waves. First-order waves appeared with a mean frequency of 128 ± 14/min. The mean wave amplitude was 0.150 ± 0.03 mV, and the mean duration was 0.43 ± 0.05 s. They were closely correlated with the electrocardiogram and blood pressure changes. Second-order waves appeared with a mean frequency of 15.9 ± 4.4/min. They were characterized by a mean duration of 2.69 ± 1.5 s. The mean amplitude of the discharge was 0.205 ± 0.157 mV for the second-order wave, they were correlated with the animal's respiratory action. Third-order waves appeared with a mean frequency of 4.03 ± 1.07/ min. They were characterized by a mean duration of 11.81 ± 5.3 s. The mean amplitude of the discharge was 0.345 ± 0.232 mV for the third-order wave and they were associated with the autonomic control of the lumen of the blood vessel. For the first time the usefulness of the electromyography method in monitoring changes in the vascular smooth muscle cell of pig abdominal aorta was proved.

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Membrane electrical mechanism of basilar artery constriction and pial artery dilation by norepinephrine.

Cited by 39 publications

References 19 publications

Mechanisms of action of noradrenaline and carbachol on smooth muscle of guinea‐pig anterior mesenteric artery.

Mechanisms of action of noradrenaline and carbachol on smooth muscle of guinea‐pig anterior mesenteric artery.

Pharmacological characterization of postjunctional α‐adrenoceptors in cerebral arteries from the sheep

Myoelectric activity of the muscular layer of the abdominal aorta in pigs in vivo

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