Contraction of porcine ocular ciliary muscle by epidermal growth factor-urogastrone

Epidermal growth factor-urogastrone (EGF) caused a concentration-dependent contractile response in porcine ocular ciliary muscle preparations. The half-maximal contraction was observed at 23 ng/ml EGF (4 nM). The contractile action of EGF, which was not abolished by the removal of extracellular calcium, was not affected by atropine, tetrodotoxin, phentolamine and indomethacin. In addition to causing contractions on its own, the contractile action of EGF was potentiated in the presence of prostaglandin E1 and vasopressin. Our data point to a potential role for EGF in the regulation of ciliary muscle tension.