Alpha 1- and alpha 2-adrenergic response in human isolated skin arteries during cooling.
1. Dose-response curves for noradrenaline, phenylephrine and clonidine were determined isometrically in 2-mm cylindrical segments from human skin arteries at 24 degrees C and compared to those previously reported at 37 degrees C. 2. Noradrenaline (3 x 10(-10)-3 x 10(-4) M) induced dose-dependent contraction and the sensitivity was increased during cooling. Phentolamine (10(-6) M), prazosin (10(-6) M) or yohimbine (10(-6) M) produced a higher rightward shift of the control curve for noradrenaline during cooling. 3. Phenylephrine (10(-11)-3 x 10(-4) M) and clonidine (10(-11)-10(-6) M) caused dose-dependent contraction and the sensitivity of the arteries was augmented at 24 degrees C. 4. The arteries also showed a lower maximal contraction to the adrenergic agonists used and KCl (50 mM) during cooling. 5. The results suggest that cooling: (a) increases sensitivity of postjunctional alpha 1- and alpha 2-adrenoceptors in human skin arteries and (b) depresses contractility of these arteries to alpha-adrenergic stimulation and direct activation of vascular smooth muscle.
Gómez
B
B
Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma, Madrid, Espãna.
Borbujo
J
J
García-Villalón
A L
AL
Nava-Hernández
E
E
Valle
J
J
García
J L
JL
Diéguez
G
G
D000328:Adult; D000368:Aged; D001158:Arteries / Q000502:physiology*; D003000:Clonidine / Q000494:pharmacology; D003080:Cold Temperature; D004347:Drug Interactions; D006801:Humans; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply*; D015016:Yohimbine / Q000494:pharmacology
D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D015016:Yohimbine; D003000:Clonidine; D011188:Potassium; D009638:Norepinephrine; D011224:Prazosin; D010646:Phentolamine