The pH of Systemic Blood in Normal and Hypertensive Dogs,Determined by Means of a Syringe Type Glass Electrode. ∗

Abstract

This experiment was performed in order to determine whether any pH changes of the systemic blood of dogs accompany the development of hypertension produced by partial constriction of the renal artery. 1 , 2 Thirteen dogs were used; 4 were hypertensive at the beginning of the experiment; in 4 others hypertension was produced during the period of observation; the remainder served as controls. Over a period of 90 days blood was taken frequently from the saphenous vein directly into a special syringe-type glass electrode. The pH was then measured with a Beckman pH meter.

This glass electrode was a modification of the type developed by Maclnnes and Belcher 3 with a capacity of 0.5 cc; it was so constructed that a sterile hypodermic needle could be attached to its tip.† The venous pressure was usually sufficient to force the blood through the straight inner tube of the electrode; occasionally slight stasis was necessary. Constant temperature of the electrode was insured by hanging it in a saturated potassium chloride solution which was kept at 37.5 ° C by circulating water. This potassium chloride solution served further as a liquid junction between the glass electrode and the reference half-cell. The electrode was calibrated with buffer solutions of known pH and was checked between each sample of blood. The accuracy of the measurements was 0.03 pH units.

Although only 0.5 cc of blood was necessary to fill the glass electrode completely, usually another 0.5 cc of blood was passed through it to make sure that the blood was of the same composition as that in the vein. Before taking a sample, the electrode was rinsed with a solution of heparin (obtained from Connaught Laboratories, University of Toronto, Canada, or Hynson, Westcott and Dunning, Inc., Baltimore, Md.) in 0.9% sodium chloride.