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...

The present study was designed to measure norepinephrine release during sympathetic nerve stimulation and evaluate the presynaptic inhibitory and facilitatory actions of a-adrenoceptor and /3-adrenoceptor agonists respectively, in the isolated perfused kidney of normotensive WistarKyoto (WKY) and spontaneously hypertensive rats (SHR). Periarterial nerve stimulation (0.25 to 32 Hz) caused a sign...

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...

BACKGROUND Experimental studies on the effects of alpha 2-adrenoceptors on regional coronary blood flow in normal and ischemic myocardium are highly controversial. A beneficial effect on regional ischemic myocardium has been demonstrated in different animal preparations with either alpha 2-adrenoceptor blockade or stimulation. Animal studies also demonstrated that postsynaptic alpha 2-adrenocep...

Background. Experimental studies on the effects of a2-adrenoceptors on regional coronary blood flow in normal and ischemic myocardium are highly controversial. A beneficial effect on regional ischemic myocardium has been demonstrated in different animal preparations with either a2-adrenoceptor blockade or stimulation. Animal studies also demonstrated that postsynaptic a2-adrenoceptors mediate v...

It has previously been shown that chronic inflammation causes a reduction in sympathetic nerve-mediated vasoconstriction in rat knees. To determine whether this phenomenon is due to an alteration in smooth muscle adrenoceptor function, the present study compared the alpha-adrenoceptor profile of blood vessels supplying the anteromedial capsule of normal and chronically inflamed rat knee joints....

McDougall, Jason J. Abrogation of a-adrenergic vasoactivity in chronically inflamed rat knee joints. Am J Physiol Regulatory Integrative Comp Physiol 281: R821–R827, 2001.— It has previously been shown that chronic inflammation causes a reduction in sympathetic nerve-mediated vasoconstriction in rat knees. To determine whether this phenomenon is due to an alteration in smooth muscle adrenocepto...

Hyperhomocysteinemia is a known risk factor for cardiovascular diseases, but the underlying mechanisms of this pathology are complex. We aimed to evaluate the effect of hyperhomocysteinemia in vasorelaxations induced by alpha(1D)-adrenoceptor agonists. Vascular reactivity of rat carotid artery to the alpha-adrenoceptor agonist, phenylephrine, was enhanced in hyperhomocysteinemia. Mechanical rem...