The coronary efflux of radioactive 3',5'-cyclic adenosine monophosphate (cAMP) and adenosine from isolated guinea pig hearts was measured following selective prelabelling of coronary endothelial adenine nucleotides with 10 nM [2,8,5'-3H] adenosine. Intracoronary infusion of adenosine and its derivatives 5'-N-ethyl-carboxamide-adenosine (NECA), (-)-N6-(R-phenyl-isopropyl)-adenosine (R-PIA), and ...

The purpose of the present study was to characterize adenosine receptors in human atrial and ventricular myocardium. In isolated electrically driven preparations, adenosine produced "direct" negative inotropic effects in atrial myocardium (AT). In ventricular myocardium (VE), it only had negative inotropic properties when force of contraction had been stimulated with isoprenaline ("indirect" ef...

Previous studies showed that mice with pristane-induced arthritis (PIA) and those protected from the disease by preimmunization with mycobacterial 65-kDa heat shock protein (hsp65), possess raised immune responses to hsp65. Thus, a paradox exists whereby T cells from both arthritic and hsp65-protected animals proliferate vigorously in response to the same Ag. Here we demonstrate that T cells fr...

cAMP content and protein phosphorylation were determined in unlabeled and 32P-labeled guinea pig ventricular myocytes. Isoproterenol (10 nM, 37 degrees C, 10 seconds) increased cAMP content (236%) and phospholamban (265%) and troponin I (135%) phosphorylation in ventricular myocytes. When isoproterenol (0-300 nM) and the A1-adenosine receptor agonist (-)-N6-phenylisopropyladenosine (PIA, 1 micr...

Cia5 is a locus on rat chromosome 10 which regulates the severity of collagen- and pristane-induced arthritis (CIA and PIA). To refine the region toward positional identification, Cia5 subcongenic strains were generated and studied in PIA and CIA. The protective effect of the telomeric locus Cia5a was confirmed in both models. A second arthritis severity locus (Cia5d) was identified within the ...

Twenty-five methicillin-resistant Staphylococcus aureus (MRSA) isolates were characterized by staphylococcal protein A gene typing and the ability to form biofilms. The presence of exopolysaccharides, proteins, and extracellular DNA and RNA in biofilms was assessed by a dispersal assay. In addition, cell adhesion to surfaces and cell cohesion were evaluated using the packed-bead method and mech...

We examined the mechanism by which adenosine inhibits prolactin secretion from GH3 cells, a rat pituitary tumour line. Prolactin release is enhanced by vasoactive intestinal peptide (VIP), which increases cyclic AMP, and by thyrotropin-releasing hormone (TRH), which increases inositol phosphates (IPx). Analogues of adenosine decreased prolactin release, VIP-stimulated cyclic AMP accumulation an...

We previously demonstrated that both adenosine receptor activation and direct activation of protein kinase C (PKC) decrease unloaded shortening velocity (V(max)) of rat ventricular myocytes. The goal of this study was to further investigate a possible link among adenosine receptors, phosphoinositide-PKC signaling, and V(max) in rat ventricular myocytes. We determined that the adenosine receptor...

Central stimulant actions of 10 methylxanthines in mice correlate with affinities for adenosine receptors labeled with N6-[3H]cyclohexyladenosine. Affinities of methylxanthines for adenosine receptors are consonant with central levels attained at behaviorally effective doses. The much higher concentrations of methylxanthines required to influence benzodiazepine receptor binding do not correlate...

We examined the effects of adenosine and its analogs on sympathomimetic responses of pithed rats to electrical stimulation of preganglionic sympathetic nerves (ES) or to injections of nicotine, phenylephrine (PE) or isoproterenol (ISO). Four physiological indices of sympathetic neurotransmission were measured: blood pressure, heart rate and contractions of smooth muscle in vas deferens and eyel...