Excessive renal efferent sympathetic nerve activity contributes to hypertension in many circumstances. Although both hemodynamic and tubular effects likely participate, most evidence supports a major role for α-adrenergic receptors in mediating the direct epithelial stimulation of sodium retention. Recently, it was reported, however, that norepinephrine activates the thiazide-sensitive NaCl cot...

Background—Catecholamines hasten cardiac relaxation through b-adrenergic receptors, presumably by phosphorylation of several proteins, but it is unknown which receptor subtypes are involved in human ventricle. We assessed the role of b1and b2-adrenergic receptors in phosphorylating proteins implicated in ventricular relaxation. Methods and Results—Right ventricular trabeculae, obtained from fre...

Di- and tripeptides, as well as peptidomimetic drugs such as cephalexin (CFX), are absorbed by enterocytes via the oligopeptide transporter PepT1. We recently showed that the alpha(2)-adrenergic agonist clonidine increases CFX absorption in anaesthetized rats. Herein, we investigated whether alpha(2)-adrenergic receptors can directly affect PepT1 activity in a clone of the differentiated human ...

Intact lymphocytes from patients with cystic fibrosis (CF) produce significantly (P less than 0.001) less adenosine 3':5' cyclic monophosphate (cAMP) than normal lymphocytes in response to isoproterenol (10(-8)-10(-4) M), although the basal cAMP content and the response to prostaglandin E1 are normal. Obligate heterozygotes for CF have significantly (P less than 0.005) reduced cAMP response to ...

Activation of renal alpha-adrenergic receptors induces vasoconstriction, proximal tubular reabsorption of sodium, and inhibition of renal release. Excesses of these effects are present in varying degrees in animal models of, and in patients with, "essential" hypertension. Since essential hypertension is genetically determined, we sought abnormalities of renal alpha-adrenergic receptors in the O...

Neuropeptide Y and Sympathetic Nervous System in Blood Pressure Regulation To the Editor: We read with great interest the recent article by Dr Michalkiewicz and his colleagues1 dealing with a possible link between neuropeptide Y (NPY) and sympathetic nervous system in the NPY-transgenic rats. The results of their presented study demonstrated that overexpression of endogenous NPY in the transgen...

Adrenergic hyporesponsiveness in congestive heart failure has been understood previously in terms of a reduction in beta-adrenergic receptors. We have examined another hypothesis, one that states the stimulatory guanine nucleotide regulatory protein (Gs) that couples the beta-adrenergic receptor to adenylate cyclase activity is also decreased in congestive heart failure. In addition to the 40% ...

'H](±)Carazolol, " newly available ^-adrenergic receptor antagonist, has been used to characterize /f-adrenergic receptor subtypes present in membrane vesicles derived from canine ventricular myocardium and canine lung. [H](±)Carazolol binding is saturable, of high affinity, and in displaceable by /J-adi-e.nergic agents in accordance with their known pharmacological potencies. The interaction o...

Adrenergic hyporesponsiveness in congestive heart failure has been understood previously in terms of a reduction in .8-adrenergic receptors. We have examined another hypothesis, one that states the stimulatory guanine nucleotide regulatory protein (Gs) that couples the j3-adrenergic receptor to adenylate cyclase activity is also decreased in congestive heart failure. In addition to the 40% decr...

The hypotensive action of methyldopa has been linked to production of the metabolites methyldopamine and methylnorepinephrine in brain. We have studied the effect of long-term (72 hour) intravenous infusions of methyldopa to awake restrained spontaneously hypertensive rats and normotensive Wistar-Kyoto control animals to look for differences in hypotensive effect, differences in concentrations ...