Faculty Collaboration Database

Muscarinic and ganglionic blocking properties of atropine compounds in vivo and in vitro: time dependence and heart rate effects. Can J Physiol Pharmacol 1995 Apr;73(4):483-90

Date

04/01/1995

Pubmed ID

7671191

DOI

10.1139/y95-061

Scopus ID

2-s2.0-0029016381 (requires institutional sign-in at Scopus site)   7 Citations

Abstract

High doses (3 mg/kg) of methylatropine nitrate have been used in vivo to produce long-lasting muscarinic blockade during physiologic experiments. At these levels, the possibility exists that ganglionic blockade may also be responsible for some heart rate effects. Therefore, the effects of methylatropine nitrate (0.0012-2.4 mg.kg(-1)) and atropine sulfate (0.0036 - 0.060 mg.kg(1)) were evaluated in vivo using conscious dogs and in vitro using canine right atria and isolated stellate ganglia. The lowest doses of either agent given in vivo caused bradycardia, while intermediate doses induced excess tachycardia. High doses of methylatropine nitrate transiently decreased the heart rate, followed by slow recovery. In vitro using the canine right atria, neither drug caused pacemaker shifts nor directly altered the atrial rate, but postvagal tachycardia occurred with acetylcholine challenge and was prevented by metoprolol or 6-hydroxydopamine. In vitro studies using the canine stellate ganglia indicate that both agents depressed postganglionic compound action potentials at high doses. In conclusion, with high-dose methylatropine nitrate, ganglionic blockade yields the mechanism for a reduction of excess tachycardia as well as a likely explanation for opposing chronotropic effects in conscious and anesthetized dogs. In experimental studies where high doses of atropine compounds are used for long-term muscarinic blockade, it is possible that ganglionic blocking effects may also be produced.

Author List

Vicenzi MN, Woehlck HJ, Boban M, McCallum B, Atlee JL, Bosnjak ZJ

Author

Harvey J. Woehlck MD Professor in the Anesthesiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Action Potentials
Animals
Atropine
Atropine Derivatives
Biological Clocks
Dogs
Electrocardiography
Ganglionic Blockers
Heart Rate
In Vitro Techniques
Muscarinic Antagonists
Stellate Ganglion
Synaptic Transmission
Time Factors