The interaction between noradrenaline activation and distension activation of the rabbit ear artery.

Speden, R. N.; Warren, D.

doi:10.1113/jphysiol.1986.sp016117

Cited by 16 publications

(18 citation statements)

References 31 publications

(54 reference statements)

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“…Myogenic constriction is enhanced by various agonists including NE [32][33][34], and, in turn, agonist sensitivity of arterioles may be modulated by the prevailing amount of myogenic activation [14,35]. Interestingly, reduction in transmural pressure inhibited intrinsic tone but had little effect on tone induced by KC1 or the ai-agonist phenylephrine in hamster cheek pouch arterioles studied in vitro [6].…”

Section: Discussionmentioning

confidence: 99%

In vitro Analysis of Alpha-Adrenoceptor Interactions with the Myogenic Response in Resistance Vessels

Ikeoka

Nishigaki²,

Ohyanagi³

et al. 1992

J Vasc Res

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The interaction of alpha 1- and alpha 2-adrenoceptor constriction of isolated rat cremaster small arteries (mean diameter +/- SEM, 114 +/- 5 microns) with the myogenic mechanism was examined with in vitro videomicroscopy. Microdissected vessels were double-cannulated with glass micropipets in a tissue bath, and intraluminal pressure was set at 65 mm Hg baseline pressure. Norepinephrine (NE) concentration-response curves were obtained alone and in the presence of prazosin or rauwolscine to establish the concentration of NE required to selectively stimulate alpha 1- or alpha 2-adrenoceptors. A bimodal response was produced by NE alone, indicating interaction with more than one receptor population. Rauwolscine and prazosin each produced dextral displacement at low (< 0.1 microM) NE concentrations. However, while prazosin exhibited competitive antagonism, rauwolscine did not antagonize NE at concentrations > or = EC50 value. Thus, both alpha 1- and alpha 2-adrenoceptors mediate constriction at low NE concentrations, but only alpha 1-receptors contributed to constriction at intermediate and high concentrations. These data are in contrast to previous findings for the same vessels studied in vivo. Diameter responses to increases and decreases in transmural pressure from baseline were examined in the relaxed (passive) state with nitroprusside present, during spontaneous intrinsic tone, and during induced alpha 1- or alpha 2-tone (EC20 concentration of NE plus rauwolscine or prazosin). Myogenic constriction during increases in lumen pressure and myogenic inhibition of tone during decreases in pressure were greatest during alpha 2-tone, less during intrinsic tone and least during alpha 1-tone.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionmentioning

confidence: 99%

In vitro Analysis of Alpha-Adrenoceptor Interactions with the Myogenic Response in Resistance Vessels

Ikeoka

Nishigaki²,

Ohyanagi³

et al. 1992

J Vasc Res

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“…Thus, both pressure and NE increase Ca 2+ within SMCs [29]. Furthermore, these stimuli interact, with NE augmenting myogenic responses to pressure [30, 31]and pressure enhancing the sensitivity of vessels to NE [30, 32]. Nevertheless, the effects of such changes in vasomotor tone on conducted responses have remained undefined, particularly in feed arteries that can be governed by sympathetic nerves [4].…”

Section: Discussionmentioning

confidence: 99%

Role of Smooth Muscle Activation in Conduction of Vasodilation along Isolated Hamster Feed Arteries

Walker

Segal²

1998

J Vasc Res

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Vasodilation originating within a muscle is conducted into feed arteries, but the determinants of conduction along feed arteries are undefined. We have investigated the effect of vasomotor tone on conducted vasodilation in feed arteries of the hamster retractor muscle. Unbranched segments (length, 2–3 mm) were isolated, cannulated, and studied in vitro at 37°C while pressurized to 25 mm Hg, 75 mm Hg (in vivo pressure), or 120 mm Hg in the absence and presence of norepinephrine (NE, 10^–7 M + 10^–6 M propanolol). Internal diameter decreased (p < 0.05) as pressure increased (85 ± 7, 73 ± 4, 66 ± 6 µm, respectively), confirming myogenic reactivity. Acetylcholine (ACh, 0.1 M) was delivered (1 µA, 500 ms) from a micropipette; vasomotor responses were recorded at the site of release (‘local’) and at distances up to 1,500 µm (‘conducted’) along the vessel. There were no responses to ACh at 25 mm Hg. However, dilations (diameter change, µm) were pronounced at 75 mm Hg (local: 22 ± 3; conducted: 18 ± 2, respectively), without further change at 120 mm Hg. NE constricted vessels (p < 0.05) at each pressure (to 65 ± 9, 57 ± 6, and 56 ± 8 µm, respectively); this enabled both local (14 ± 2 µm) and conducted (10 ± 1 µm) vasodilation at 25 mm Hg but was without effect on conduction at 75 or 120 mm Hg. Our findings indicate that conducted responses plateau at a physiological level of myogenic tone. Whereas NE had no effect on conduction under normal or hypertensive conditions, it enabled conduction during hypotension. We conclude that pressure and NE influence the ability of conducted vasodilation to govern muscle blood flow.

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“…It is also difficult to compare the data of wire myograph with pressure myograph because the vasomotion is reflected in different measurements: tension and diameter, respectively. Although the pressure myograph can be regulated for isometric measurements, 25,27 it has not received the broad utility of a wire myograph.…”

Section: Comparison With Wire and Pressure Myographsmentioning

confidence: 99%

Vasoactivity of Blood Vessels Using a Novel Isovolumic Myograph

Lu¹,

Kassab²

2007

Ann Biomed Eng

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The vasoactivity of blood vessel is impaired by cardiovascular disease. The ex-vivo measurements of vasoactivity (wire and pressure myographs) have some inherent difficulties in the characterization of pharmacodynamics and biomechanics. Here, we introduce a novel isovolumic myograph which allows simultaneous measurement of both dynamic pressure and dimensional changes during vasoconstriction or vasodilation. The principle of the isovolumic myograph is based on the utility of a hydraulically closed system with low compliance such that contraction against an incompressible fluid increases the pressure with the closed system while dilation decreases it. We demonstrate the sensitivity and utility of the new technique by the response of elastic (carotid), muscular (femoral) arteries, and femoral veins. The results show characteristic dynamic pressure response for each vessel type. Furthermore, our results show a Hill-type equation for the tension-velocity relation for smooth muscles as well as characteristic curves for each contraction. These novel findings for blood vessels will advance our knowledge of endothelium and vascular smooth muscle mechanics and pharmacodynamics.

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The interaction between noradrenaline activation and distension activation of the rabbit ear artery.

Cited by 16 publications

References 31 publications

In vitro Analysis of Alpha-Adrenoceptor Interactions with the Myogenic Response in Resistance Vessels

In vitro Analysis of Alpha-Adrenoceptor Interactions with the Myogenic Response in Resistance Vessels

Role of Smooth Muscle Activation in Conduction of Vasodilation along Isolated Hamster Feed Arteries

Vasoactivity of Blood Vessels Using a Novel Isovolumic Myograph

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