Pupillary response to atrial natriuretic factor in rabbits

This study was designed to evaluate the pupillary and intraocular pressure (IOP) response to exogenously administered atrial natriuretic factor (ANF) in rabbits. Dose-response studies were conducted by administering intracameral (i.c.) ANF (0.1-5 micrograms). The effect of route of administration was evaluated by administering ANF (5 micrograms/kg) intravenous (i.v.) subcutaneous (s.c.) and intraperitoneal (i.p.). In a final study, normal rabbit serum or ANF antiserum were administered i.c. In all studies, pupillary diameter (PD) and IOP were evaluated. Intracameral administration of ANF (0.1-5 micrograms) produced a significant (P less than 0.01) dose-dependent unilateral miosis without affecting IOP. Peripheral (i.v., s.c., i.p.) administration ANF did not affect PD or IOP. Finally, ANF antiserum did not affect PD significantly. These data suggest that ocular, but not circulating ANF may contribute to regulate pupillary function. The mechanism of the miotic response to ANF probably involves interactions with other autonomic neurotransmitters because immunoneutralization of endogenous ocular ANF was without measurable effect.