Functional Dependence of the Ciliary Epithelium ATPase Activity and Intraocular Pressure on the Autonomic Nervous System

Regulation of intraocular pressure by autonomic nerves of the eye was studied using three types of denervation: sympathectomy, ciliarectomy or coagulation of the parasympathetic nerves (around the optic nerve). Intraocular pressure, inflow and outflow were registered manometrically using a constant pressure infusion technique. ATPase activities in the ciliary processes were demonstrated histochemically and assayed fluorometrically. Special attention was paid to the biochemical characteristics of the ciliary body NaK‐ATPase activity. A kinetic fluorometric method for NaK‐ATPase was developed. Intraocular pressure decreased after ciliarectomy simultaneously with a decrease in inflow of the aqueous humour. Ciliary body‐iris NaK‐ATPase activity also decreased. The changes in the ocular fluid dynamics after coagulation of the parasympathetic nerves tended to be the same. Intraocular pressure decreased as well as NaK‐ATPase activity. Sympathectomy, however, did not change ocular fluid dynamics or NaK‐ATPase activity. The ciliary body‐iris NaK‐ATPase activity seemed to have the characteristics of the transport enzyme found in other organs. It was activated by Na+, K+ Mg++ could be inhibited by ouabain. Activity was optimum when the Mg++/ATP ratio was about 1 and the optimal pH both for Mg‐ and NaK‐ ATPase was 8.1. The results give further support to the theory that intraocular pressure is under nervous control. This regulation is mediated by decreased inflow, which in turn is reflected by a lowered NaK‐ATPase activity in the ciliary processes.