A Comparative Study on the Contraction Induced by High K/Na Deficient Solution in the Trachea, Gall Bladder and Urinary Bladder in Guinea-Pig

Abstract

In the present paper, a comparative study of high K solution was carried out on the mechanical response, wet and dry weights of tissue, and extracellular space of 14C-sorbitol in the trachea, gall bladdei, and urinary bladder of guinea-pig. Hyperosmotic addition of KCl to the physiological solution produced a sustained contraction, while isosmotic substitution of K for Na in the physiological solution induced a contraction followed by a small sustained one in the trachea, gall bladder or urinary bladder. At 120 min after application of the substituted KCl, Na deficient solution, it increased cell water content in the smooth muscle cells of the trachea or gall bladder, but did not change that in the urinary bladder. Both the inhibition of contraction and the swelling in the trachea or gall bladder were prevented by the hyperosmotic application of sucrose or NaCI. The substitution for NaCI with the K salts with more permeable anions (l->NO3->Cl-) produced a greater inhibition of contraction in the trachea and gall bladder. Although the impermeable anion C2H5CO2- did not inhibit the contraction in thetrachea, this anion partially inhibited it in the gall bladder. On the other hand, the inhibition of contraction in the urinary bladder was prevented by addition of pyruvate, oxalacetate or NaCI. From these results, it is suggested that the inhibition of contraction in the trachea and gall bladder, quiescent smooth muscle, is probably due to cell swelling and that the inhibition of contraction in the urinary bladder, spontaneously active smooth muscle, is mainly caused by an inhibition of glucose utilization by Na deficiency in the medium. However, the gall bladder probably has an intermediate property between the trachea and urinary bladder in high K-induced contraction.