Sodium and potassium in canine gastric mucosa and smooth muscle

¹ Section of Physiology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota

Sodium content of unstimulated canine gastric mucosa of the body area measures 71 ± 1 mEq, of pyloric gland area, 75 ± 1 mEq, and of gastric smooth muscle, 73 ± 1 mEq/kg wet wt. Potassium content of these tissues is 65 ± 1, 58 ± 1, and 72 ± 2 mEq/kg wet wt., respectively. Volume of distribution of radioiodinated serum albumin (Risa) is 71 ± 8, 104 ± 16, and 45 ± 10 ml/kg wet wt. Erythrocyte content is 13 ± 1, 7 ± 1, and 8 ± 1 ml/kg wet wt. Tissues also were analyzed after 150 min of stimulation with histamine and methacholine, the only significant changes being a fall in sodium content of body mucosa and pyloric gland area. Values for extravascular sodium and potassium were calculated by subtracting amounts in Risa space and erythrocytes from total tissue values. On stimulation, values for extravascular sodium tend to fall and those for potassium tend to rise. Sodium of all the tissues comes to within 90% of equilibrium with radiosodium (Na²⁴) in plasma within 5 min, and only 3–5 mEq/kg wet wt. of sodium in the tissues fails to equilibrate with plasma Na²⁴ in 150 min.