To investigate the impairment of beta-adrenoceptor responsiveness in human hypertension, we evaluated the effect of an oral salt load (400 mEq/day of NaCl for 7 days) on plasma catecholamine concentrations and beta-adrenoceptor-mediated effects in 11 young patients with mild essential hypertension. Responses of heart rate and plasma cAMP to isoproterenol administration were used as indices of b...

The present study examined the influence of alpha-2 adrenoceptor ligands on circling behavior in rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway. The alpha-2 adrenoceptor agonists, clonidine and UK 14304, inhibited both the ipsilateral rotation induced by the indirect dopaminergic agonist, methylphenidate, and the contralateral circling induced by the direct dopamine...

Pyridostigmine bromide (PB) is a reversible cholinesterase inhibitor used routinely in the treatment of myasthenia gravis and recently by the US Army as a prophylactic agent against potential nerve gas attack in the Persian Gulf War. Pyridostigmine has been implicated as one of several possible causative factors associated with Persian Gulf illnesses. To investigate toxic interactions between P...

Pharmacological characteristics of the canine isolated splenic artery were investigated by the cannula insertion method for observing vascular responses to vasoactive agents and periarterial nerve stimulation. Four alpha-adrenoceptor agonists and tyramine induced vasoconstrictions in a dose-dependent manner, and the order of potency was noradrenaline (NA) > phenylephrine > clonidine > methoxami...

Cerebral blood volume and intracranial pressure may be modified by influences on cerebral veins. The known adrenergic innervation of cerebral veins and their sensitivity to norepinephrine raised the question, whether pial veins can be selectively influenced through adrenoceptors in vivo. Therefore, alpha 1 and alpha 2 adrenoceptor agonists and antagonists were locally injected into the perivasc...

Effects of prizidilol and nipradilol (K-351), beta-adrenoceptor antagonists with vasodilator action, on blood pressure and heart rate were studied in normotensive conscious rabbits after i.v. administration. In addition, we investigated relationships between plasma drug concentrations and beta-adrenoceptor blocking activity as estimated by the inhibition of isoproterenol-induced tachycardia and...

Ultra-low doses of non-selective α2-adrenoceptor antagonists augment acute spinal morphine antinociception and block morphine tolerance; however, the receptor involved in mediating these effects is currently unknown. Here, we used tail flick and paw pressure tests on the rat to investigate the acute analgesic and tolerance-inducing effects of spinal morphine and norepinephrine alone or in combi...

To date, no studies have investigated coronary vasomotor control of myocardial O2 delivery (MDO2) and its modulation by the autonomic nervous system in the porcine heart during treadmill exercise. We studied 8 chronically instrumented swine under resting conditions and during graded treadmill exercise. Exercise up to 85% to 90% of maximum heart rate produced an increase in myocardial O2 consump...

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...