PROSTAGLANDIN-F2-ALPHA EFFECTS ON ISOLATED RHESUS-MONKEY CILIARY MUSCLE

Purpose. The effects of prostaglandin (PG)F-2 alpha on the contractile response in the longitudinal and coronal vectors of the isolated rhes us monkey ciliary muscle were studied. Methods. Fresh rhesus monkey ci liary muscle strips from young and middle-aged animals were mounted in an apparatus capable of monitoring contractile force simultaneously i n the two vectors. The responses to PGFB(2 alpha), were measured and c ompared to those produced with 1 mu M carbachol. Results. PGF(2 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. Co nclusions. The relaxation of precontracted ciliary muscle by PGF(2 alp ha) may help explain how a single topical dose of this prostanoid incr eases uveoscleral outflow and antagonizes resting myopia in the living monkey.