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Prostaglandin E2 and the bovine sphincter pupillae
British Journal of Pharmacology
|November 1, 1973
Summary
Bovine eye sphincter muscles release prostaglandin E(2), a substance that influences muscle tone. This prostaglandin likely acts as a local hormone, contributing to sphincter muscle contraction.
Area of Science:
- Ophthalmology
- Pharmacology
- Physiology
Background:
- The bovine isolated sphincter pupillae muscle preparation is a model for studying ocular muscle function.
- Prostaglandins are known mediators of various physiological processes, including smooth muscle contraction.
Purpose of the Study:
- To investigate the release and function of biologically active substances from the bovine sphincter pupillae.
- To identify the substance responsible for maintaining sphincter muscle tone and its potential role as a local hormone.
Main Methods:
- Incubation of isolated bovine sphincter pupillae in Krebs solution.
- Measurement of spontaneous release of biologically active substances.
- Assessment of the effects of exogenous prostaglandins (E and F types) on atonic sphincter muscle.
- Evaluation of prostaglandin antagonist SC-19220 on prostaglandin E(2)-induced responses.
Main Results:
- A substance tentatively identified as prostaglandin E(2) was released from the bovine sphincter pupillae.
- Prostaglandin E(2) release correlated with sphincter muscle tone.
- Prostaglandins E and F induced sustained contractions in the atonic sphincter, with E(2) being most potent.
- Prostaglandin antagonist SC-19220 selectively antagonized prostaglandin E(2) effects and caused relaxation at higher concentrations.
Conclusions:
- Prostaglandin E(2) is likely produced by the bovine sphincter pupillae and may function as a local hormone.
- Prostaglandin E(2) contributes to the tonic contraction of the sphincter pupillae.
- Prostaglandins do not appear to modulate neurotransmission in this muscle preparation.