1. The effect of ambient temperature on the properties of adrenoceptors mediating inotropic responses was assessed in isolated frog hearts on the basis of the effects and tissue uptake of alpha- and beta-adrenoceptor antagonists. 2. At temperatures of 23degree C and above inotropic responses to adrenaline were antagonized by propranolol (0-4-4-0muM), but were unaffected by phentolamine (26-5muM) and were potentiated by phenoxybenzamine (POB) (0-7-29-5muM). Below 17degree C the activity of propranolol was reduced at least tenfold, and the alpha-adrenoceptor antagonists inhibited responses to both adrenaline and isoprenaline, but not those to CaCL2. 3. The responses of hearts exposed to POB at 14degree C and then tested, after thorough washing, at both 14 and 24degree C were similarly inhibited at both temperatures, i.e. the usual beta-adrenoceptor response did not appear at the higher temperature. Conversely, exposure to POB at 24degree C produced only potentiation at both test temperatures. 4. Parallel to the reciprocal changes in their blocking actions, significantly more (14C)propranolol was retained by hearts exposed at high temperatures and significantly more (3H)POB was bound to the myocardium at low temperatures. Changes ...Continue Reading
A comparison of the binding characteristics of the beta-adrenoceptor antagonists 3H-dihydroalprenolol and 125I-iodocyanopindolol in rat liver
Identification of alpha1-adrenergic receptors and their involvement in phosphoinositide hydrolysis in the frog heart
Attenuated cardiovascular effects of prostaglandin I2 and prostaglandin F2 alpha in cold acclimated American bullfrogs, Rana catesbeiana.
Cardiovascular responses to catecholamines at 12 degrees C in the American bullfrog (Rana catesbeiana)
The differential effect of cooling on the responses of splenic capsular and vascular smooth muscle to nerve stimulation and noradrenaline
Epinephrine stimulates prostaglandin synthesis by bullfrog lung from warm-acclimated, but not cold-acclimated, animals
Impaired inotropic responses to alpha-adrenergic stimulation in experimental left ventricular hypertrophy.
Evidence against the temperature-dependent interconversion of histamine H1- and H2-receptors in the guinea-pig ileum
Comparative aspects of cardiac adrenoceptors: characterization of the beta 2-adrenoceptor as a common "adrenaline"-receptor in vertebrate hearts
Thiol reactivity and the molecular individuality of alpha- and beta-adrenoreceptors in rat liver plasma membranes
Altered in vitro adrenergic responses of dog detrusor msucle after chronic bladder outlet obstruction
Electrical and mechanical effects induced by cold temperatures in the ventricle of isolated Rana ridibunda hearts
Adrenergic Receptors: Trafficking
Adrenergic receptor trafficking is an active physiological process where adrenergic receptors are relocated from one region of the cell to another or from one type of cell to another. Discover the latest research on adrenergic receptor trafficking here.