Abstract:
:Clonidine was administered to isolated guinea pig right atria in order to characterize its chronotropic activity and its interaction with other chronotropic agents at the postjunctional level. Clonidine either had no significant effect (10(-7)--10(-4) M) or decreased (10(-3) M) atrial rate. Pretreatment of the atria with clonidine noncompetitively antagonized (10(-6)--10(-4) M) the positive chronotropic actions of isoproterenol, and competitively antagonized (10(-4) M) the negative chronotropic actions of pilocarpine. At doses of 10(-6) or 3 X 10(-6) M, clonidine also noncompetitively antagonized the positive chronotropic effects of 4-methylhistamine and glucagon. The results show that clonidine antagonizes both adrenergic and cholinergic influences on atrial rate at the postjunctional level and suggest that the antagonism of adrenergic influences does not involve a direct interaction with beta-adrenergic receptors.
journal_name
Can J Physiol Pharmacoljournal_title
Canadian journal of physiology and pharmacologyauthors
Rodgers RL,Tenner TE Jr,Laher IE,McNeill JHdoi
10.1139/y80-006subject
Has Abstractpub_date
1980-01-01 00:00:00pages
28-33issue
1eissn
0008-4212issn
1205-7541journal_volume
58pub_type
杂志文章abstract::Slow alpha2-globulin (salpha2G), a high molecular weight glycoprotein, appears as a component of rat serum in a wide variety of both physiologic and pathologic conditions, including pregnancy; it is also present in the neonate. In the present study, the protein was detectable in serum after 6 to 10 days, and was prese...
journal_title:Canadian journal of physiology and pharmacology
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journal_title:Canadian journal of physiology and pharmacology
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journal_title:Canadian journal of physiology and pharmacology
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