Effects of four calcium channel blockers on central cardiovascular control.

The cardiovascular effects of intravenous and intracisternal administration of low doses of calcium channel blockers (nicardipine: 0.3 to 10 micrograms/kg; nifedipine: 0.01 to 10 micrograms/kg; verapamil: 0.

Rilmenidine (S 3341) and the sympathoadrenal system: adrenoreceptors, plasma and adrenal catecholamines in dogs.

1. The effects of rilmenidine, a new alpha 2-adrenoreceptor agonist with antihypertensive properties, were investigated on plasma catecholamines, blood cell adrenoreceptors and adrenal medullary function. 2.

Involvement of cholinergic mechanisms in the central cardiovascular actions of nicardipine in dogs.

The involvement of cholinergic mechanisms in the central cardiovascular effects of a dihydropyridine, nicardipine, was investigated in pentobarbital-anaesthetized normotensive dogs. Nicardipine (1 microgram/kg) injected intracisternally (i.c.

A study of the action of clonidine on secretion from the adrenal medulla in dogs.

The effects of clonidine on adrenal catecholamine (adrenaline and noradrenaline) secretion were investigated in chloralose-anaesthetized dogs. Intravenous administration of clonidine (10 and 20 micrograms kg-1) induced a decrease in both adrenal catecholamine secretion rates and cardiovascular parameters (blood pressure and heart rate). In contrast, a dose of 5 micrograms kg-1 was ineffective.

Effects of calcium entry blockers on blood pressure and heart rate in neurogenic hypertensive dogs.

The hypotensive and negative chronotropic effects of 5 calcium entry blockers (verapamil 200 micrograms/kg IV; diltiazem 300 micrograms/kg IV; nifedipine 5 micrograms/kg IV; nicardipine 50 micrograms/kg IV; and bepridil 5 mg/kg IV) were compared in control normotensive and acute neurogenic hypertensive anaesthetized dogs. Acute neurogenic hypertension was induced by sino-aortic denervation (SAD). In control normotensive dogs, all drugs (except bepridil) induced a slight and transient decrease in blood pressure.