Ion transport and metabolism in slices of guinea-pig seminal-vesicle mucosa

Abstract

Conditions of incubation are described under which slices of seminal-vesicle mucosa of the guinea pig retained most of their K in the absence of O2 and of Na in the medium. A comparison has been made betw concentrations, the concentrations of easily hydrolyzable phosphate and the rates of respiration and anaerobic glycolysis. The tissue maintained its initial concentration of easily hydrolyzable phosphate, and retained most of its K during both aerobic and anaerobic incubation for 45 min. at 37[degree] in standard medium containing NaCl. The addition of 2,4-dinitrophenol and iodoacetate or a reduction of the temperature caused a loss of easily hydrolyzable phosphate and of K, and a gain of Na. The rough correlation between the maintenance of the concentrations of Na and K, and of easily hydrolyzable phosphate, is compatible with a dependence of active cation transport on labile phosphate esters such as adenosine triphosphata. Lowering the temperature of incubation from 37[degree] to 27[degree] did not affect the concentrations of Na, K and Cl- found in the tissue after both aerobic and anaerobic incubation, although QO2 and QN2 CO2 were reduced by about 50%. Incubation at 17[degree] and 1[degree], however, caused a loss of K, gains of Na and Cl- and a further fall in the metabolic quotients. It appears that the energy supply was sufficient for the active transport of ions at 27[degree] but not at 17[degree] and 0[degree]. Tissue slices incubated in media in which NaCl had been partially or completely replaced by either choline chloride or sucrose contained Na in a concentration roughly proportional to that of the medium. Their K concentration, however, remained unchanged in sucrose medium and fell only about 10 [mu]moles/g of whole tissue in choline chloride medium. Incubation in Na-free media caused a fall in QO2 from 6.4 in standard medium to about 4 in the sucrose or choline chloride media. The tissue K concentration after incubation in Na-free media was lowered only between 4 and 14 [mu]moles/g of whole tissue by a reduction of temperature from 37[degree] to 1[degree], or an addition of 2,4-dinitrophenol plus iodoacetate or an o.nission of glucose and glutamate (which were usually added to the tnedium). In contrast, these factors caused a large loss of K (24-36 [mu]moles/g of whole tissue), which was balanced by a gain of Na, after incubation in standard medium. The results suggest that K can be retained passively, by a Donnan equilibrium created by non-diffusible internal anions, in slices of seminal-vesicle mucosa in the absence of metabolic energy, provided that Na in the medium is replaced by sucrose or choline chloride. Potassium retention by the tissue in standard medium, however, depended on metabolic energy, because in its absence K was replaced by Na.