title: Insensitivity to the alpha2-adrenergic receptor blocker yohimbine hydrochloride and occurrence of spontaneous platelet macroaggregation (SPMA) in diabetes.
abstract: We report here a study of platelet aggregation in diabetes, induced by epinephrine and its inhibition by yohimbine hydrochloride (YH), an alpha(2)-adrenergic receptor-blocking agent. Interestingly, emergence of spontaneous platelet macroaggregation (SPMA) was observed in six out of 75 cases in the absence of any agonist. The SPMA cases were strongly associated with insensitivity to YH (in contrast with non-SPMA cases) when epinephrine was used as an agonist. We suggest that the observed correlation is a result of over expression of platelet alpha(2)-adrenoceptors in such subjects. The quantitative nature of the effect is supported by the observation that addition of YH at higher concentration (more than 5 microM) led to restoration of the adrenergic receptor-blocking activity of the said agent. Eventually for non-SPMA subjects YH exhibited blocking activity even at lower concentration. The aggregation profile and the platelet morphology of the SPMA cases had distinctive features as compared to microaggregates formed in other diabetic subjects (non-SPMA cases).
authors.affiliation: Institute of Haematology and Transfusion Medicine, Medical College, Kolkata, India.
authors.forename: Prabir
authors.initials: P
authors.lastname: Lahiri
authors.forename: Utpal
authors.initials: U
authors.lastname: Chaudhuri
authors.forename: Anjan Kr
authors.initials: AK
authors.lastname: Dasgupta
authors.forename: S N
authors.initials: SN
authors.lastname: Ray
authors.forename: S
authors.initials: S
authors.lastname: Saha
authors.forename: P
authors.initials: P
authors.lastname: Mukherjee
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D002478:Cells, Cultured; D003920:Diabetes Mellitus / Q000503:physiopathology*; D004336:Drug Antagonism; D004351:Drug Resistance; D004837:Epinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D015016:Yohimbine / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D015016:Yohimbine; D004837:Epinephrine