Role of the endothelium in the response to cholinoceptor stimulation of rabbit ear and femoral arteries during cooling

Abstract

1 The role of the endothelium in the effects of cooling on the response to cholinoceptor stimulation of the rabbit central ear (cutaneous) and femoral (non-cutaneous) arteries was studied using 2 mm long cylindrical segments.2 Concentration-response curves for acetylcholine (I0-9-IO-OM), methacholine (10-9-1iO-M) and sodium nitroprusside (IO-9-IO-4M) were isometrically recorded in arteries under conditions, with and without endothelium or following pretreatment with the nitric oxide-synthesis inhibitor N0-nitro-Larginine methyl ester (L-NAME, 10-6-3 x 10-M) at 37°C and at 24°C (cooling). 3 Ear and femoral arteries showed endothelium-dependent relaxation to acetylcholine and methacholine at 37°C and 24°C. The extent of relaxation of the control ear arteries, but not of the control femoral arteries, to acetylcholine and methacholine increased during cooling. 4 L-NAME (10-6-3 x IO-4 M) reduced in a concentration-dependent way the response of ear arteries to acetylcholine at both 37°C and 24°C, this reduction being more potent at 37°C. L-Arginine (10-'-10-M) reversed in a concentration-dependent manner the inhibitor effects of 10-5 M L-NAME at both temperatures. 5 Sodium nitroprusside caused a concentration-dependent relaxation in both arteries that was endothelium-independent. However, the extent of relaxation to this nitrovasodilator in ear and femoral arteries was lower at 24°C. 6 These results suggest that cooling augments the reactivity of cutaneous (ear) arteries, but not that of non-cutaneous (femoral) arteries to cholinoceptor stimulation by endothelium-mediated mechanisms. Cooling could therefore facilitate the stimulated release of endothelial nitric oxide in cutaneous vessels.

Moderate hypothermia attenuates α1-adrenoceptor-mediated contraction in human varicose spermatic vein: The role of nitric oxide(Short communication)

“…Treatment with L-NAME also increased the sensitivity to phenylephrine at 28°C, suggesting that the production of NO in the endothelium can be increased under moderate hypothermia. Thus, the response of the spermatic vein to moderate hypothermia in this study is in agreement with that of the cutaneous vessels of different species (9,17). The reason for this discrepancy may be related to differences between arteries and veins, skin vascular regions, and perhaps species.…”

“…It has vasodilator activity and its local level is controlled by biosynthesis from the inactive precursor L-arginine. As vascular relaxants, the endothelium can produce NO from L-arginine (9).…”

Role of the Nitric Oxide on Relaxation of the Human Umbilical Artery during Cooling

“…It has also been shown that the relaxation to cholinergic stimulation of ear artery, but not of femoral artery, from rabbit was increased during cooling. 28) Theˆnd-ings in guinea-pig myocardium and aorta support our results; Saito et al 4) reported that the vasorelaxant eŠects of K ＋ channel openers, NIP-121, cromakalim, and pinacidil, were greatly reduced during cooling. However, the mechanism underlying the eŠect of cooling to diŠerent agents is not clear.…”

“…Furthermore, Bodellson et al 31) reported that cooling speciˆcally alters the sensitivity to various drugs in diŠerent parts of the vascular systems; in the rat jugular vein, cooling markedly augments the contraction to 5-HT and it has been found that this augmentation is dependent of an intact endothelium. Monge et al 28) reported that the relaxations of ear arteries, but not of femoral arteries, from rabbits to cholinergic stimulation is increased during cooling, probably by an increased production of nitric oxide in the activated endothelium at low temperature. It is also reported that the increased sensitivity of the relaxation in ear arteries, but not in femoral arteries, to histamine found during cooling seems to be independent of the release of nitric oxide.…”

Role of calcium in contractile responses of calf cardiac vein during cooling

“…The endothelium can produce nitric oxide from L-arginine which causes vascular relaxation (Palmer et al, 1988). In addition to agonist-mediated constriction, limited evidence suggests that vascular smooth muscle responsiveness to nitric oxide and related factors can be influenced by temperature (Karaki and Nagase, 1987;Monge et al, 1993;Garcia-Villalon et al, 1995). Recently, we studied the effects of temperature on the contractile responses of smooth muscle preparations in a variety of vessels from different species and observed that the contractile responses were temperature-dependent, with the endothelium appearing to have no role in these responses (Atalik et al, 2000;Atalik et al, 2001a;Atalik et al, 2003).…”