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Uptake kinetics and ion requirements for extraneuronal uptake of noradrenaline by arterial smooth muscle and collagen
Author(s) -
GILLESPIE J. S.,
TOWART R.
Publication year - 1973
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.1476-5381.1973.tb08186.x
Subject(s) - vascular smooth muscle , kinetics , biophysics , chemistry , medicine , ion transporter , ionic bonding , ion , endocrinology , smooth muscle , biology , physics , organic chemistry , quantum mechanics
Summary1 The ionic requirements for noradrenaline uptake into vascular smooth muscle cells were studied by perfusing rabbit isolated ear arteries with noradrenaline (10 −3 M) either in Krebs solution or in Krebs solution modified by altering the concentration of one or more ion. Noradrenaline uptake was measured by quantitative microphotometry. 2 Some uptake into smooth muscle continued in isotonic sucrose in the absence of all ions. Omission of Na + from the Krebs solution partially inhibited uptake as did high (100 m m ) K + . Omission of K + , Ca ++ or Mg ++ had no effect on uptake. Lithium was able completely to substitute for Na + . 3 Alteration in ion concentration did not affect the binding of noradrenaline to collagen. 4 The kinetics of uptake of noradrenaline into smooth muscle were analysed and found to be saturable with a Km of 4·9 × 10 −4 M. 5 It is concluded that the ionic requirements of the transport mechanism for the uptake of noradrenaline by vascular smooth muscle show a relatively low specificity.