Muscarinic acetylcholine receptors play important roles in both the peripheral and central nervous systems. They play a prominent role in the brain, and muscarinic antagonists are known to interfere with wakefulness, memory and learning. In addition, they are part of sympathetic and parasympathetic functioning, exercising profound influences on heart rate and sweating as well as on bronchial and gastrointestinal smooth muscle tone and glandular activity. Volatile anesthetics have been shown to inhibit muscarinic signaling, and some non-volatile anesthetic agents, such as ketamine and althesin, similarly appear to affect the system. These actions on muscarinic receptors could explain some of the effects as well as side-effects of the drugs. However, the studies are difficult to interpret as most times mixtures of receptor subtypes were used; single, high doses of anesthetic were studied; many studies address effects on binding rather than functional assays; and no molecular localization of the site of action was attempted. The molecular cloning of the five subtypes of muscarinic receptor now allows us to study these interactions in isolation and more detail. In this proposal, m1, m2 and m3 receptors muscarinic receptors will be expressed in Xenopus oocytes, and the effects of halothane, isoflurane, desflurane, ketamine, propofol and althesin on their functioning will be studied.
Specific aims are (1) to compare these anesthetics as to their interactions with the muscarinic receptor subtypes; (2) to determine their sites of action in the muscarinic signaling cascade; (3) to localize using mutation studies the intramolecular sites of action of anesthetic drugs on muscarinic signaling; and (4) to compare the findings in Xenopus oocytes with those obtained in mammalian cells. The results of these studies will provide a better understanding of anesthetic-protein interactions in general, and of anesthetic interference with the clinically important muscarinic signaling system in particular.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29GM052387-03
Application #
2392229
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Project Start
1995-04-01
Project End
2000-03-31
Budget Start
1997-04-01
Budget End
1998-03-31
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Virginia
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
001910777
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
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Kamatchi, G L; Durieux, M E; Lynch 3rd, C (2001) Differential sensitivity of expressed L-type calcium channels and muscarinic M(1) receptors to volatile anesthetics in Xenopus oocytes. J Pharmacol Exp Ther 297:981-90
Kamatchi, G L; Tiwari, S N; Durieux, M E et al. (2000) Effects of volatile anesthetics on the direct and indirect protein kinase C-mediated enhancement of alpha1E-type Ca(2+) current in Xenopus oocytes. J Pharmacol Exp Ther 293:360-9
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