Arterial Myogenic Properties of the Spontaneously Hypertensive Rat

Abstract

When subject to a transmural pressure gradient resistance arteries develop a spontaneous, intrinsically initiated contraction which varies according to the pressure stimulus and occurs in the absence of vasoconstrictor agonists. Such pressure-dependent active changes in vascular tone are indicative of the vascular myogenic response and contribute to autoregulation and the setting of total peripheral resistance and hence blood pressure regulation. The myogenic behaviour of blood vessels provides the background tone upon which other vasomotor influences act. Hypertension is associated with a raised vascular resistance and in this article the evidence for increased myogenic activity contributing to the raised vascular resistance is reviewed. Although there are some cases that provide evidence for exaggerated myogenic responsiveness in resistance arteries taken from hypertensive animals it is not possible to conclude that enhanced myogenic contractile responses within normal pressure ranges contribute to the raised total peripheral resistance. However, the myogenic tone of the resistance arteries of the various vascular beds is subject to differing modulatory influences in hypertensive animals and their normotensive controls which may contribute to the aetiology of hypertension. Experimental Physiology (2002) 87.5, 527-534. 2399

Myogenic tone in mouse mesenteric arteries: evidence for P2Y receptor-mediated, Na+, K+, 2Cl− cotransport-dependent signaling

“…Second, the apparent affinity of sustained contractile responses was higher for UDP compared to UTP (Fig. 3B), which is consistent with the rank-order potency for P2Y 6 rather than for other UTP-and UDP-sensitive receptors, such as P2Y 2 and P2Y 4 [40,43]. Third, UTP-induced constrictions were sharply suppressed in the presence of 10 μM MRS2567 (Fig.…”

“…of three independent experiments are shown P2Y 13 ) have been cloned from mammalian cDNA libraries [14]. Among them, P2X 1 , P2X 2 , P2X 4 , P2X 5 , P2Y 2 , P2Y 4 , and P2Y 6 mRNA species and proteins interacting with anti-P2X 1 , anti-P2Y 2 , and anti-P2Y 6 antibodies have been detected in rodent small arteries [36][37][38][39][40]. Our results show that transient and sustained constrictions of mouse mesenteric arteries evoked by ATP and UTP, respectively, are mainly mediated by P2X 1 and P2Y 6 receptors.…”

“…6). Side-by-side with the [Ca 2+ ] i signaling precipitated by P2Y 6 receptors, MT may involve PKC activation that, in turn, leads to heightened [Ca 2+ ] i sensitivity of the contractile machinery via myosin light chain kinase phosphorylation [3].…”

Flow-Mediated Dilation of the Radial Artery Is Offset by Flow-Induced Reduction in Transmural Pressure

“…We cannot exclude an additional "myogenic" type response to change in transmural pressure having an additional influence on arterial tone and diameter. However, because the myogenic response to an increase in transmural pressure is vasoconstriction, 15,16 any such response when transmural pressure decreases would be opposite to that observed.…”

Sustained conduction of vasomotor responses in rat mesenteric arteries in a two‐compartment in vitro set‐up

“…However, there are good arguments to believe that tone in vascular networks also needs to be controlled at longer time scales. Notably, myogenic tone and sympathetic drive are among the factors that set the baseline level of tone 22. A highly heterogeneous baseline tone would not only cause a disturbed distribution of flow in networks, but also a strongly increased peripheral resistance.…”