Acetylcholine-evoked potassium and sodium transport in rat lacrimal segments: evidence for a sodium-chloride co-transport system.
An investigation was made of the effects of acetylcholine (ACh) on transmembrane movements of potassium (K+) and sodium (Na+) in isolated segments of rat lacrimal glands. ACh elicited dose-dependent and transient increases in K+ concentration in the effluent (K+ release). The ACh-induced K+ outflow was unaffected by either pre-treatment of lacrimal segments with loop diuretics (frusemide, piretanide and bumetanide, all 10(-4) M) or replacement of chloride (Cl-) in the physiological salt solution with nitrate (NO3-). In contrast, ACh caused a significant (P less than 0.001) reduction in Na+ concentration in the effluent (Na+ uptake). The ACh-evoked Na+ uptake was sensitive to loop diuretics and Cl- removal. Pre-treatment of tissue with ouabain (10(-3) M) resulted in a marked sustained K+ release. ACh produced a further increase in K+ efflux in the continuing presence of ouabain. Incubation of the tissue with 10 mM-tetraethylammonium (TEA) resulted in an uptake of K+. The result suggest the presence of a diuretic-sensitive Na+-Cl- co-transport system in lacrimal acinar cell membranes.
Singh
J
J
School of Applied Biology, Lancashire Polytechnic, Preston.
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004232:Diuretics / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D007765:Lacrimal Apparatus / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012964:Sodium / Q000378:metabolism*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D004232:Diuretics; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D012964:Sodium; D000109:Acetylcholine; D011188:Potassium