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Effects of KCl on 45 Ca uptake and efflux in the rat vas deferens
Author(s) -
Hay D.W.P.,
Wadsworth R.M.
Publication year - 1984
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.1476-5381.1984.tb10096.x
Subject(s) - verapamil , vas deferens , nifedipine , efflux , chemistry , extracellular , calcium , medicine , endocrinology , intracellular , stimulation , biochemistry , biology , organic chemistry
1 The effects of KCl 160 m m on 45 Ca uptake and efflux in the rat isolated vas deferens were investigated using a modification of the lanthanum method and a superfusion system respectively. 2 In the prostatic half, basal cellular 45 Ca uptake was 679 ± 21 nmol g −1 tissue wet weight and KCl 160 m m increased this by 155%. In the epididymal half, basal cellular 45 Ca uptake was 730 ± 28 nmol 45 Ca g −1 and KCl 160 m m increased this by 46%. 3 Verapamil 2.04 JAM or nifedipine 0.29 μ m had no or little effect on basal 45 Ca efflux or on basal 45 Ca uptake. The KCl‐induced increase in 45 Ca uptake in both halves was inhibited by verapamil 2.04 μ m or nifedipine 0.29 μ m , concentrations which markedly reduce the contractile response. It is concluded that high K + contracts the rat vas deferens by stimulation of the entry of extracellular Ca 2+ to the intracellular compartment. 4 KCl 160 m m produced a large, rapid and reversible increase in the rate of 45 Ca efflux into Ca 2+ ‐containing and Ca 2+ ‐free Krebs‐Henseleit solutions, which was not inhibited by verapamil 2.04 μ m , nifedipine 0.29 μ m or nitroprusside 1,678 μ m . 5 The relative size of the slow component of 45 Ca efflux was larger in the prostatic half compared to the epididymal half of bisected tissues, suggesting that the postulated high affinity binding sites are predominant in this region. However, the rates of the fast and slow components of 45 Ca efflux from prostatic and epididymal halves were identical. KCl 160 m m produced a similar increase in 45 Ca efflux in prostatic and epididymal halves.