Premium
THE EFFECT OF STIMULUS INTENSITY ON α‐ADRENOCEPTOR‐MEDIATED FEED‐BACK CONTROL OF NORADRENALINE RELEASE
Author(s) -
HARPER BARBARA,
HUGHES I. E.
Publication year - 1978
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.1476-5381.1978.tb17284.x
Subject(s) - phentolamine , endocrinology , stimulus (psychology) , medicine , stimulation , chemistry , calcium , tritium , biophysics , biology , psychology , physics , nuclear physics , psychotherapist
1 Mouse vas deferens stimulated transmurally (2.5 Hz, 2–32 V, 40–620 mA, for 45 s) responded with a twitch and a secondary contraction. Both responses were abolished by cinchocaine and were voltage‐dependent. 2 In tissues previously incubated with [ 3 H]‐(—)‐noradrenaline, stimulation also produced an increase in tritium overflow from the tissue. Phentolamine increased tritium overflow by 19% at high stimulus intensities (30 V, 600 mA) and by 130% at low stimulus intensities (11 V, 200 mA). 3 It is concluded that α‐adrenoceptor‐mediated feed‐back control of noradrenaline release is more marked at low stimulus intensities and that this is compatible with a role for calcium ions in this control mechanism.