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Calcium entry blockade and adrenergic vascular reactivity in hypertensives: Differences between nicardipine and diltiazem
Author(s) -
Pedrinelli Roberto,
Panarace Giovanni,
Salvetti Antonio
Publication year - 1991
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1991.14
Subject(s) - diltiazem , nicardipine , vasodilation , propranolol , medicine , vasoconstriction , forearm , norepinephrine , brachial artery , pharmacology , endocrinology , calcium , blood pressure , anatomy , dopamine
The interference of nicardipine and diltiazem infused into the brachial artery at systemically ineffective rates, with the forearm vascular response to graded exogenous norepinephrine, was evaluated in hypertensive patients. Nicardipine (1 and 3 μg/dl forearm tissue/min in both absence and presence of propranolol) increased forearm blood flow (venous plethysmography) and antagonized dose dependently the vasoconstrictor effect of norepinephrine, suggesting that functional α‐antagonism may participate in the vasodilating and possibly the antihypertensive effect of the drug. On the contrary, no antagonism but rather potentiation of the responses to norepinephrine occurred after diltiazem (0.5 and 1 μg/dl forearm tissue/min). Because intra‐arterial propranolol abolished that potentiating action of the drug, whereas the local vasodilation to isoproterenol was clearly reduced, diltiazem probably interfered with β‐adrenergic receptor‐mediated vasorelaxing mechanisms in human forearm arterioles. The data further stress the heterogeneity of calcium entry blockers in humans. Clinical Pharmacology and Therapeutics (1991) 49 , 86–93; doi: 10.1038/clpt.1991.14