Secretory effect of prostaglandins on the rabbit lacrimal gland [formula omitted

Abstract

Fluid secretion from the cannulated excretory duct of the rabbit lacrimal gland was collected in microcapillary pipette at 10 min intervals. Secretion rate and electrolyte concentrations (Na+, K+ and Cl-) in the lacrimal fluid samples were determined before and after injections of small doses of prostaglandins (PGE 1, PGE 2, PG F 1α, PGF 2α, 15 epi-PGF 2α, PGF 2β, PGA l & PGA 2) into the external maxillary artery. Only PGE 1 had a dose-dependent stimulatory effect on the lacrimal gland secretion. The maximum secretion rate which was induced by PGE 1 (25 μg/kg) was 7.2 ± 0.9 μl/10 min. Na + concentration in the fluid secretion stimulated by PGE 1 was increased; however, K + and Cl − concentrations were not changed. Pretreatment with atropine (50 μg/kg, I.A.) failed to prevent the stimulatory effect of low doses of PGE 1. On the other hand, the secretory responses were abolished when propanolol (3 mg/kg, I.A.) was administered prior to PGEI. The results suggest that fluid secretion of the rabbit lacrimal gland in response to PGEI may be caused by excitation of the sympathetic ganglia and/or by direct action on β-receptors in the acinar cells.