Role of the endothelium on the response to adrenoceptor agonists of rabbit aorta during cooling

Abstract

The role of the endothelium in the effects of cooling on the response to alpha1- and alpha2-adrenoceptor agonists of rabbit aorta was studied. The contractions induced by clonidine (10(-9)-3 x 10(-4) M) and xylazine (10(-7)-10(-3) M) but not phenylephrine (10(-9)-3 x 10(-4) M) and methoxamine (10(-9)-3 x 10(-4) M) were enhanced in endothelium-denuded or N(G)-nitro-L arginine methyl- ester (L-NAME) (10(-5) M) pretreated rabbit aorta. The sensitivity, but not the maximal response, of both alpha1- and alpha2-adrenoceptor agonists was significantly lower at 28 degrees C (cooling) than at 37 degrees C. Endothelium removal did not affect the action of cooling. These results were taken as evidence for the specificity of alpha2-adrenoceptor agonists on the production and release of nitric oxide from vascular endothelium. The results suggest that the endothelium seems to have no role in the cooling-induced responses of both alpha1- and alpha2-adrenoceptors.

Effects of cooling and warming on 5‐hydroxytryptamine‐ and acetylcholine‐induced contractions of human umbilical vessels: role of nitric oxide

“…In the present study, we also investigated the role of nitric oxide in cooling-and warming-induced responses. In previous studies, we observed similar findings in different tissues such as rabbit aorta [14], calf coronary artery and cardiac vein [15,16]. This suggested that during cooling or warming the response to the vasoconstrictors is not modulated by nitric oxide.…”

“…The temperatures utilized in this study; 28°C, for cooling was considered to be 'moderate cooling' temperature accordingly to our previous studies [14,15] and 41°C for warming was chosen to include body temperature experienced during passive or exertional warming under physiological or pathophysiological conditions. Furthermore, data from in vitro preparations warmed to 40°C or higher are equivocal [12,25].…”

Diabetes mellitus- and cooling-induced bladder contraction: an in vitro study

“…The ice-water test is a simple supplementary urodynamic test that increases the precision of the diagnosis of infant detrusor overactivity (Geirsson et al, 1999). The temperature utilized in this study; 28ºC, for cooling was considered to be "moderate cooling" temperature accordingly to our previous studies (Atalık et al, 2000;Atalık et al, 2001;Atalık et al, 2008). In our study, compared with the control responses at 37ºC, cooling increased both the sensitivity and the maximum responses to ACh and KCl in both non-diabetic and STZ-induced diabetic urinary bladder.…”

“…It has been shown that in diabetic animals, contractile responses of the urinary bladder to muscarinic agonists are inconsistent. Some investigators have reported increased responses (Tong et al, 2002;Nsabimana and Ojewole, 2008), while others have reported decreased responses (Licoln et al, 1984;Longhurst et al, 1986), or no change in contractile responses (Luheshi and Zar, 1991;Atalık et al, 2000) of diabetic urinary bladder smooth muscle strip to muscarinic agonists.…”

Role of the nitric oxide on rosuvastatin-induced relaxation of the calf cardiac vein during cooling

“…The calf cardiac vein is easily accessible smooth muscle preparations and there is a limited information (13-16) about the effects of temperature in these vessels and the effects of cooling were generally studied with contractile agents. Furthermore, to our The temperature utilized in this study; 28 °C, for cooling was considered to be 'moderate cooling' temperature accordingly to our previous studies (13,17).…”