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Abstract
PURPOSE: The effects of prostaglandin (PG)F2 alpha on the contractile response in the longitudinal and coronal vectors of the isolated rhesus monkey ciliary muscle were studied. METHODS: Fresh rhesus monkey ciliary muscle strips from young and middle-aged animals were mounted in an apparatus capable of monitoring contractile force simultaneously in the two vectors. The responses to PGF2 alpha were measured and compared to those produced with 1 microM carbachol. RESULTS: PGF2 alpha consistently relaxed the carbachol precontracted ciliary muscle in a dose-dependent manner with equal potency and efficacy in both vectors, but it did not alter the tone of muscle strips at resting tension. CONCLUSIONS: The relaxation of precontracted ciliary muscle by PGF2 alpha may help explain how a single topical dose of this prostanoid increases uveoscleral outflow and antagonizes resting myopia in the living monkey.