This project investigates the underlying mechanisms by which drugs affect the contraction of smooth muscles. Smooth muscles are the type of muscles that line blood vessels, cause the movements of the walls of the stomach and intestine, and control the opening and closing of the pupils of the eye. These muscles as important as they are for normal blood pressure, digestion, and vision in humans, are nevertheless considered to be more "primitive" than skeletal or cardiac muscle. Smooth muscles are the main type of muscles in lower organisms, such as snails or worms, where they can be studied with fewer technical difficulties than in vertebrate animals. Understanding the mechanisms by which endogenous substances or drugs control the contraction of these muscles may help us better understand hypertension, blindness or problems in digestion. One substance found in both humans and lower animals is serotonin, which is released by blood clots and can contract blood vessel walls and amplify the effects or other contractile substances, thereby, exacerbating the effect of the clot. This research studies the mechanism by which serotonin amplifies the contraction of smooth muscle in the sea snail, Aplysia. Methods have been developed to isolate smooth muscle cells so that the contraction and electrical properties of individual cells may be studied. The studies examine the effect of serotonin and drugs on these properties.
