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Effects of Na + and K + on the uptake of metaraminol by rabbit ventricular slices
Author(s) -
PATON D. M.
Publication year - 1971
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.1476-5381.1971.tb09936.x
Subject(s) - metaraminol , ouabain , chemistry , potassium , inhibitory postsynaptic potential , sodium , ion transporter , biophysics , biochemistry , membrane , endocrinology , biology , organic chemistry , blood pressure
Summary1 The ionic dependence of [ 3 H]‐metaraminol transport by rabbit ventricular slices was studied. 2 Transport was Na + dependent. Choline, Li + , K + , Rb + or Cs + could not be substituted for Na + . 3 Transport was K + dependent. Rb + and Cs + , but not Li, could be substituted for K + , their relative potencies being K + =or >Rb + >Cs + >Li + . Higher concentrations of K + , Rb + , Cs + and Li inhibited [ 3 H]‐metaraminol transport. 4 The inhibitory effects on transport of either a marked reduction in the concentration of Na + or of omission of K + were rapidly reversible on exposure of slices to Krebs solution. 5 The inhibitory effect of ouabain on [ 3 H]‐metaraminol transport was markedly time dependent, being significantly increased by preincubation with ouabain. The inhibitory action of ouabain was not affected, however, by the Na + concentration present during preincubation. 6 An inwardly directed Na + gradient did not increase [ 3 H]‐metaraminol transport in slices in which Na + pumping had been prevented by 10 −5 m ouabain, 4° C, omission of K + or by metabolic inhibition. 7 These findings provide additional evidence that the Na + and K + activated adenosine triphosphatase may participate in the transport of metaraminol and related amines. In the absence of Na + pumping, induced Na + gradients were unable to produce transport of amine as would be predicted by the co‐transport model proposed by Bogdanski & Brodie (1969).