Circadian rhythms are daily cycles that control our sleep-wake patterns, hormone release, and body temperature, and are found in virtually all life forms. Because our internal clock runs just over 24 hours, our bodies set it to match day length using environmental cues such as light. Information about light levels travels from the eyes to a brain structure called the pineal gland, which adjusts...

The role of adrenergic agents in augmenting proximal tubular salt and water flux, was studied in a preparation of freshly isolated rabbit renal proximal tubular cells in suspension. Norepinephrine (NE, 10(-5) M) increased sodium influx (JNa) 60 +/- 5% above control value. The alpha adrenergic antagonist, phentolamine (10(-5) M), inhibited the NE-induced enhanced JNa by 90 +/- 2%, while the beta...

The alpha 2 and beta 2 adrenergic receptors, both of which are activated by epinephrine, but which can be differentiated by selective drugs, have opposite effects (inhibitory and stimulatory) on the adenylyl cyclase system. The two receptors are homologous with each other, rhodopsin, and other receptors coupled to guanine nucleotide regulatory proteins and they contain seven hydrophobic domains...

The highly specific a -adrenergic agonist, dexmedetomidine, has hypnotic-sedative, anesthetic-sparing and analgesic effects, and it 2 protects neurons against ischemia. The a -adrenergic agonist, phenylephrine, does not share dexmedetomidine’s pharmacological 1 21 21 properties, although both dexmedetomidine and phenylephrine increase free cytosolic Ca ([Ca ] ) in astrocytes, and most of i dexm...

Demonstration of A Ipha and Beta Adrenergic Receptors in Canine Cerebral Vasculature • The cerebral vascular effects of various adrenomimetic agents were examined in 12 isolated canine brains perfused with blood at constant flow. Changes in cerebral vascular resistance (CVR) and the magnitude of pressor or depressor responses observed following drug injection were examined. The presence of alph...

BACKGROUND Although alpha-adrenergic receptors are present in both normal and failing human left ventricular myocardium and mediate a positive inotropic effect in several other species, it is not known whether stimulation of myocardial alpha-adrenergic receptors exerts a positive inotropic effect or contributes to basal contractile state in vivo in humans. METHODS AND RESULTS We studied 15 pa...

Abnormalities in activity of the endothelin (ET) system have been widely reported in a number of cardiovascular disease states such as hypertension and heart failure. Although the vascular responses to ET are well established, the interaction between ET and other important modulators of blood pressure, such as the sympathetic nervous system, are less understood. Previous reports implicate ET si...

We evaluated the G protein selectivity of chimeric M1 and M2 muscarinic cholinergic receptors in which either the third intracellular (I3) loop or the N-terminal portion of this loop (the I3N peptide) was replaced by the corresponding sequence from the beta 1-adrenergic receptor. The chimeras retained agonist-dependent G protein regulatory activity, but were completely promiscuous among potenti...

Mirtazapine (MIR) is an antidepressant which enhances noradrenergic and serotonergic 5-HT1A neurotransmission via antagomism of central alpha2-adrenergic autoreceptors and heteroreceptors. The drugs does not inhibit noradrenaline and serotonin reuptake but blocks the 5-HT, and 5-HT3 receptors and has high affinity only for central and peripheral histamine H1 receptors. The present study was aim...

Sympathetic nerves may play a role in vascular disorders of the eye. In the present study, we hypothesized that activation of 3-adrenergic receptors on retinal endothelial cells would promote migration and proliferation of these cells, two markers of an angiogenic phenotype. We show, for the first time, expression of 3adrenergic receptors on cultured retinal endothelial cells. Activation of the...