Effect of selective blockade of M4 cholinoreceptors by tropicamide on blood supply in brain, splanchnic azygous organs, and hindlimbs in intact rats.
Experiments on anesthetized rats carried out with a high-frequency ultrasonic system and tropicamide, a highly selective blocker of M4 cholinoreceptors, showed that the vasodilator effects observed after selective blockade of M4 cholinoreceptors are not organ-specific. Intravenous tropicamide (0.1 μg/kg body weight) transiently decreased systemic BP, elevated the linear and volume fl ow rates, and diminished vascular resistance in common carotid, superior mesenteric, and femoral arteries. At the same time, in most rats (76%) the fl ow rate in the portal vein did not change, while in 25% rats it insignificantly and temporarily increased. The hypothesis on possible involvement of M4 cholinoreceptor structures in cholinergic vasoconstriction is discussed.
Research Institute of General Pathology and Pathophysiology, Russian Academy of Medical Sciences, Moscow, Russia.
N Ya
NY
Kovalenko
D D
DD
Matsievskii
V K
VK
Reshetnyak
D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000098:blood supply*; D002339:Carotid Arteries / Q000502:physiology; D005263:Femoral Artery / Q000502:physiology; D006614:Hindlimb / Q000098:blood supply*; D008297:Male; D017538:Mesenteric Artery, Superior / Q000502:physiology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D043588:Receptor, Muscarinic M4 / Q000037:antagonists & inhibitors*; D013152:Splanchnic Circulation / Q000187:drug effects*; D014331:Tropicamide / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D018727:Muscarinic Antagonists; D043588:Receptor, Muscarinic M4; D014665:Vasodilator Agents; D014331:Tropicamide