Respiration and active sodium transport of isolated toad bladder.

Preparation of Tissue-Studies were performed on the isolated urinary bladder of the toad, Bujo marinus. Animals were pithed and the two halves of the bladder rapidly removed through a ventral incision. The tissue was rinsed in Ringer’s solution before use. For the study of the oxygen consumption of various toad tissues, small intestine, stomach, heart, ventral abdominal skin, and skeletal muscle were used. These were rapidly dissected free. Stomach and intestine were slit longitudinally and rinsed clean of contents. The heart was removed in toto by slitting the pericardium and transecting the great vessels; the organ was cut into several pieces and the blood removed by rinsing in Ringer’s solution The flat sheet of abdominal muscle was used. Medium-For most experiments a frog Ringer’s solution (sodium, 113.5; potassium, 1.88; bicarbonate, 2.38; chloride, 114.8 m.eq. per 1. and calcium, 0.89 mM; pH 8.1; and osmotic activity, 213 milliosmoles per kg. of water) was used. The sodium-free Ringer’s solution was either a magnesium chloride-Ringer solution (magnesium, 149.2; potassium, 2.38; bicarbonate, 2.38 m.eq. per 1.; calcium, 0.89 mM; pH, 8.0; osmotic activity 187 milliosmoles per kg. of water and sodium, 0 by analysis) or a choline chloride-Ringer solution (potassium, 2.38; bicarbonate, 2.38 m.eq. per 1.; sodium, 0 by analysis; calcium, 0.89 mM; osmotic activity raised to 210 milliosmoles per kg. of water by addition of a concentrated choline chloride solution, the pH of which had been adjusted to 8.1 with dilute KOH). When either of the sodium-free media was used the tissue incubated in this medium, as well as the paired bladder halves simultaneously incubated in the ordinary sodium-Ringer solution, were given