1. The whole-cell patch-clamp was used for studying the effects of various beta1- and beta2-adrenoceptor agonists and antagonists on the L-type Ca current (Ica) in frog ventricular myocytes. 2. Dose-response curves for the effects of isoprenaline (non selective beta-agonist), salbutamol (beta2-agonist), dobutamine (beta1-agonist) on ICa were obtained in the absence and presence of various conce...

Transcutaneous electrical nerve stimulation (TENS) is an analgesia inducing method with increasing applications in clinical procedures. In this study we tried to evaluate the role of the adrenergic system and its different adrenoceptor subtypes in TENS-induced analgesia. Two types of low and high frequency electrical stimuli were used in rats through needle electrodes, inserted at the base ...

BACKGROUND Current therapy for relieving bronchoconstriction may be ineffective in severe asthma, particularly in the small airways. The aim of this study was to further characterise responses to the recently identified novel bronchodilators rosiglitazone (RGZ) and chloroquine (CQ) under conditions where β-adrenoceptor agonist efficacy was limited or impaired in mouse small airways within lung ...

Adipocyte responses to adrenergic and ß-adrenoceptor(-AR) (adrenoceptor) regulation are not sufficiently understood, and information helpful for elucidating the adrenoceptor-responsive machinery is insufficient. Here we show by using immunoprecipitated kinase analysis with a phosphatidylinositol 3-kinase (PI3K) p85 antibody that PI3K activation was induced by treatment with 10 or 100 µM norepin...

Recently, a2-adrenoceptor activation was shown to play an important role in the vasoconstriction of normal coronary arteries, whereas in the presence of atherosclerosis, the activation of both a1and a2-adrenoceptors reduces coronary blood flow in humans. a2-Adrenoceptors activate pertussis toxin (PTX)-sensitive G proteins, whereas a1-adrenoceptors couple to PTX-insensitive G proteins. Thus, the...

Here, the influence of β3-adrenoceptors on catecholamine release in normotensive and spontaneously hypertensive rats was analyzed. Blood pressure was recorded through a femoral artery catheter, and cardiac output by ascending aorta flow. Time from onset of flow to maximum rise in flow indicated inotropy. Total peripheral vascular resistance (TPR) was calculated. Norepinephrine release was stimu...

The α1-adrenoceptor agonist phenylephrine and the β-adrenoceptor agonist isoproterenol have opposite effects on evoked EPSPs (eEPSPs) in the cerebral cortex. The suppressive effects of phenylephrine on eEPSPs are mediated by modulation of postsynaptic glutamate receptors, whereas enhancement of eEPSPs by isoproterenol is due to facilitation of glutamate release from presynaptic terminals. The p...

OBJECTIVES This study evaluated cardiac beta-adrenoceptor responsiveness in the elderly. BACKGROUND The hypothesis of reduced cardiac beta-adrenoceptor responsiveness in the elderly is based on a smaller increase in heart rate after administration of isoproterenol, a nonselective beta 1- and beta 2-adrenoceptor agonist. By means of dobutamine-stress-echocardiography we were able to retest the...

BACKGROUND Coronary vessel tone is modulated in part by beta-adrenergic relaxation. However, the implication of specific beta-adrenoceptor subtypes and their downstream vasorelaxing mechanism(s) in human coronary resistance arteries is poorly defined. beta3-Adrenoceptors were recently shown to vasodilate animal vessels and are expressed in human hearts. METHODS AND RESULTS We examined the exp...