The pathogenesis of primary Raynaud's phenomenon remains an enigma. Most evidence favors a local abnormality in the digital arteries as opposed to an increased activity of the sympathetic nervous system. The local fault may involve the alpha 2-adrenergic receptors, which are most important in reflex sympathetic vasoconstriction. Cooling blood vessels increase the sensitivity of alpha 2-adrenerg...

Using a perfused innervated rat heart model, we studied the sex difference in the sympathetic nerve stimulation-induced norepinephrine release and its presynaptic alpha 2-adrenergic inhibition in normoxic and ischemic conditions. During normoxic perfusion, the alpha 2-adrenoceptor antagonist rauwolscine resulted in a higher overflow of norepinephrine during nerve stimulation in females than in ...

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...

Molecular cloning of the alpha 2A-adrenergic receptor has shown that this receptor is a member of the gene superfamily of guanine nucleotide-binding protein (G protein)-coupled receptors. The alpha 2A-adrenergic receptor expressed in Chinese hamster ovary (CHO) cells attenuates and potentiates forskolin-stimulated cAMP production through independent signaling pathways. To examine the role of th...

Renal nerve stimulation-induced antinatriuresis normally is mediated through post-synaptic alpha 1-adrenergic receptors; however, prazosin-induced alpha 1-adrenergic receptor blockade is associated clinically with sodium retention and not natriuresis. To study whether alpha 2-adrenergic receptors mediate renal nerve stimulation-induced antinatriuresis after chronic prazosin treatment, Sprague-D...

The effects of a highly selective alpha-2 adrenergic agonist medetomidine and its antagonist atipamezole were studied on the delayed response task performance of aged monkeys. Medetomidine, at the dose of 1.0 micrograms/kg, improved the memory task performance, whereas atipamezole had no effect on the performance at any dose. It has earlier been shown that alpha-2 adrenergic agonists clonidine ...

In primary cultures of rat hepatocytes, addition of dexamethasone (10 microM) plus glucagon (0.5 microM) caused several-fold increases in the activities of serine dehydratase (EC 4.2.1.13), tryptophan oxygenase (EC 1.13.11.11), and tyrosine aminotransferase (EC 2.6.1.5) in 24 h. These inductions were inhibited by insulin. Addition of epinephrine or phenylephrine at 10 microM blocked these induc...

Radiocontrast nephropathy (RCN) is a common clinical problem for which there is no effective therapy. Utilizing a murine model, we tested the hypothesis that alpha(2)-adrenergic receptor agonists (clonidine and dexmedetomidine) protect against RCN induced with iohexol (a nonionic low-osmolar radiocontrast). C57BL/6 mice were pretreated with saline, clonidine, or dexmedetomidine before induction...

BACKGROUND Mental stress reliably induces increases in salivary alpha amylase (sAA), a suggested surrogate marker for sympathetic nervous system (SNS) reactivity. While stress-induced sAA increases correlate with norepinephrine (NE) secretion, a potential mediating role of noradrenergic mechanisms remains unclear. In this study, we investigated for the first time in humans whether a NE-stress-r...

We have shown recently that norepinephrine stimulates muscle cell hypertrophy in primary cultures from the neonatal rat ventricle and that this stimulation is not blocked by the beta adrenergic antagonist propranolol. The present study was done to define the adrenergic specificity of the myocyte hypertrophic response to norepinephrine. 90% pure, single-cell cultures of nongrowing myocytes were ...