Cerebrospinal fluid formation in rats and cats during treatment with timolol

Abstract

The influence of timolol upon cerebrospinal fluid formation rate has been examined in rats by the measurement of 22Na+ entry into this fluid after 10, 100, or 1000 micrograms x kg-1 i.v. and in cats by the dye-dilution measurement of new fluid formation after 30, or 3000 microgram x kg-1 i.v., or 250 micrograms x mL-1 in ventricular perfusate. In rats no change from control rates occurred. In the cats there appeared to be no effect of intraventricular timolol; however, a significant decrease of approximately 25% in the mean flow rate was seen after 40 min when drug was given i.v. at either dose level. A time study showed that no further decrease occurred within 5 h and that the observed decrease continued for at least 3 h. These findings are of interest in view of the ability of topical, intraocular, and i.v. timolol to reduce aqueous humor formation rate.

Intraocular Pressure Lowering Effects of the Renin Inhibitor ABBOTT-64662 Diacetate in Animals

“…Timolol maléate is another example of a compound that lowers blood pressure (20), slows aqueous humor formation (21) and also slows cerebrospinal fluid formation (22). Renin inhibitors have been shown to reduce systemic arterial blood pressure (7), and the present study reported on the ability of the renin inhibitor, enalkiren, to cause a reduction of IOP in animals.…”