Premium
Hypersensitivity to methoxamine in atria isolated from streptozotocin‐induced diabetic rats
Author(s) -
Canga Liliana,
SterinBorda Leonor
Publication year - 1986
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.1476-5381.1986.tb10167.x
Subject(s) - methoxamine , medicine , endocrinology , prostacyclin , inotrope , thromboxane , streptozotocin , diabetes mellitus , contraction (grammar) , stimulation , agonist , platelet , receptor
1 The reactivity to methoxamine (Met) of atria isolated from the hearts of normal and from acutely streptozotocin‐diabetic rats has been studied. 2 Met (1 × 10 −6 M) increased the tension of both normal and diabetic atria, but in diabetic atria, the dose‐response curve to Met was shifted to the left and the efficacy of Met was enhanced. 3 Inhibitors of α‐adrenoceptors blocked, in a competitive manner, the positive inotropic effect induced by Met in both types of atrial preparations. 4 Inhibitors of the cyclo‐oxygenase pathway for arachidonic acid metabolism blocked the atrial response to Met in non‐diabetic as well as in diabetic atria. The inhibition of prostacyclin synthetase prevented the effect of Met in normal atria, while blockers of thromboxane generation inhibited it in diabetic ones. 5 Agents that inhibit the activity of lipoxygenase(s) significantly reduced the positive inotropic action induced by Met in diabetic atria but failed to modify it in non‐diabetic preparations. 6 These results show that diabetic atria are more sensitive to Met than normal atria. In diabetes the response to α‐adrenoceptor stimulation could be mediated by oxidative products generated via thromboxane synthetase and lipoxygenase(s) activities; whereas in normal preparations the action of Met may involve the release of prostacyclin.