Stimulation of alpha- and beta-adrenergic receptors in the bovine mammary gland affects milking characteristics such as milk yield and peak flow rate. The aim of this study was to detect possible correlations between milkability, adrenergic receptor binding capacity and receptor expression at the mRNA level. In addition, dose-response relationships of alpha- and beta-adrenergic receptor stimula...

Breakdown of the blood aqueous barrier in the rabbit eye induces a protein leakage into the aqueous humor, seen as a flare in the anterior chamber. A barrier damage was induced by topical prostaglandin E2(PGE2), infrared irradiation of the iris, or alpha-melanocyte-stimulating hormone (alpha-MSH) given subcutaneously. The aqueous flare was measured quantitatively by means of a photoelectric ins...

The endogenous adrenergic agonists norepinephrine (NE) and epinephrine regulate vascular tone by stimulating alpha(1)-adrenergic receptors (ARs) on smooth muscle cells to cause contraction. In addition, alpha(1)-ARs also couple to growth factor pathways, through stimulation of mitogen-activated protein kinases (MAPKs). MAPKs are a family of serine-threonine kinases that include extracellular si...

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...

Selective alpha-1 and alpha-2 adrenergic agonists were used to test the hypothesis that both receptor subtypes increase transcellular Na+ transport in the nephron. Oxygen consumption (QO2) was used as an index of transcellular transport and provided a continuous dynamic record of the tubules' response to an agonist. Both alpha-1 and alpha-2 adrenoceptor agonists produced a linear dose-related i...

In this study, we examined chronic norepinephrine suppression of insulin secretion in sheep fetuses with placental insufficiency-induced intrauterine growth restriction (IUGR). Glucose-stimulated insulin secretion (GSIS) was measured with a square-wave hyperglycemic clamp in the presence or absence of adrenergic receptor antagonists phentolamine (alpha) and propranolol (beta). IUGR fetuses were...

The purpose of this study was to determine the mechanisms of dopamine regulation of phosphate uptake in opossum kidney (OK) cells, a model of proximal renal tubules. Dopamine stimulated cAMP generation and inhibited radiolabeled phosphate uptake into OK cell monolayers by 14.4 +/- 1.8%. The effect of dopamine was transient, as phosphate uptake returned toward control level by 3 h despite the co...

Both alpha- and beta-adrenergic antagonists have been utilized in an atempt to discern the site of action of prostaglandin (PG) and tetrahydrocannabinol (THC) in the eye. Both alpha- and beta-adrenergic antagonists (alpha-antagonists, phentolamine and phenoxybenzamine; beta-antagonists, propranolol and sotalol) cuased a dose-dependent reduction in intraocular pressure and blood pressure and inc...

The hypothalamic paraventricular nucleus (PVN) neurons that project to the spinal intermediolateral cell column and brainstem are important for the control of sympathetic outflow. Stimulation of alpha(1) adrenergic receptors in the PVN increases sympathetic outflow, but the cellular mechanisms remain unclear. In this study, we determined the role of alpha(1) adrenergic receptors in the regulati...

We examined the involvement of multiple monoaminergic receptors in the induction of spontaneous tail-flicks (STFs) by the open channel blocker at N-methyl-D-aspartate (NMDA) receptors, dizocilpine, and the NMDA recognition site antagonist 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP). At doses eliciting a maximal STF response, dizocilpine and CPP elevated levels of norepinephrine, ...