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DIFFERENCES IN DIHYDROERGOTAMINE ANTAGONISM OF GLUCOSE RELEASE BY CATECHOLAMINES, GLUCAGON AND ADENOSINE 3′,5′‐MONOPHOSPHATE IN RABBIT LIVER SLICES
Author(s) -
CHAN PETER S.,
ELLIS SYDNEY,
MUHLBACHOVA ELFA
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.tb17271.x
Subject(s) - medicine , glucagon , endocrinology , antagonism , dihydroergotamine , chemistry , adenosine , epinephrine , cyclic adenosine monophosphate , isoprenaline , receptor , biology , hormone , stimulation , migraine
1 Quantitative studies were made on the glucose release from rabbit liver slices in vitro induced by a range of concentrations of (—)‐adrenaline (Ad), (—)‐isoprenaline (Iso), glucagon and adenosine 3′,5′‐monophosphate (cyclic AMP) in the presence and absence of several concentrations of dihy‐droergotamine (DHE). 2 DHE (3.16 × 10 −6 m ) shifted the Ad log concentration‐response (LCR) curve to the right and also reduced the maximum response; at a higher concentration (3.16 × 10 −5 m ) it produced a greater shift to the right of the LCR curve and caused a reduction in the slope and a larger depression of the maximal responses. The LCR curve to Iso was similarly affected by this higher concentration of DHE. 3 DHE (1 × 10 −5 m ) produced no significant effect on the LCR curves of glucagon or cyclic AMP and even at 1 × 10 −4 m DHE caused only a slight depression of the maximal responses to both agonists without any modification of the lower major portions of the curves. 4 These data indicate a selective antagonism by DHE at the rabbit liver adrenoceptor and, since the maximal responses to catecholamines were depressed by a lower concentration of DHE than was required to produce a slight depression of the responses to glucagon and cyclic AMP, the antagonism of DHE against catecholamines does not appear to be at a site beyond the formation of cyclic AMP, but rather at a site more intimately related to the adrenoceptor.