Premium
EFFECTS OF METHOXYVERAPAMIL ON THE STIMULATION BY Ca 2+ , Sr 2+ AND B a2+ AND ON THE INHIBITION BY Mg 2+ OF CATECHOLAMINE RELEASE FROM THE ADRENAL MEDULLA
Author(s) -
AGUIRRE J.,
FALUTZ J.,
PINTO J.E.B.,
TRIFARÓ J.M.
Publication year - 1979
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1979.tb13699.x
Subject(s) - gallopamil , chemistry , endocrinology , medicine , extracellular , adrenal medulla , stimulation , depolarization , catecholamine , veratridine , chromaffin cell , inhibitory postsynaptic potential , calcium , biophysics , sodium , biology , biochemistry , sodium channel , verapamil , organic chemistry
1 Bovine adrenal glands were perfused with Ca 2+ ‐free Locke solution and catecholamine release was induced either by the introduction of Ca 2+ , Sr 2+ or Ba 2+ into the perfusion fluid or by the substitution of Na + by an osmotically equivalent amount of sucrose. 2 Methoxyverapamil (D600) at a concentration of 3 × 10 −4 m blocked the release of catecholamines in response to Ca 2+ , Sr 2+ or Ba 2+ stimulation but failed to block the release evoked by the omission of Na + . 3 Mg 2+ (10 to 20 m m ) blocked the release induced by Na + ‐deprivation; however, this inhibitory effect of Mg 2+ was not modified by D600. 4 D600 blocked the increase in the efflux of 45 Ca from the perfused gland induced by the introduction of Ca 2+ into the perfusion fluid and blocked the uptake of 45 Ca into adrenal medullary slices induced by K + depolarization. 5 The results suggest that Ca 2+ , Sr 2+ and Ba 2+ may enter the chromaffin cell through the same channel and that this channel is blocked by D600. Mg 2+ may enter the cell through the same Ca 2+ channel but with a high rate of permeation or it may enter through a channel which is resistant to D600. Alternatively, Mg 2+ may exert its inhibitory effect at an extracellular site.