Drug-induced changes in blood pressure and in blood sodium as measured by glass electrode

¹ Department of Anatomy, The University of British Columbia, Vancouver, Canada

By means of a glass-to-silver sodium electrode, the pattern of change in plasma sodium concentration following the administration of pressor and depressor drugs was recorded as a continuous function in a series of seven dogs. The electrode was connected into the femoral artery and its output fed into a Cary vibrating reed electrometer recording through a Grass Polygraph. The pressor response to norepinephrine, epinephrine and angiotonin was regularly accompanied by a fall in electrode potential, indicating a fall in sodium concentration. In terms of degree of change, time course, and duration of effect, each agent produced its own characteristic pattern. The depressor response to acetylcholine, histamine and isopropylnorepinephrine was accompanied by oscillations in the electrode tracing which, in general, tended to be inverse to those observed with pressor agents. The experiments demonstrate that shifts in blood pressure accompany shifts in sodium as recorded by the electrode and thus complement previous observations using blood sampling procedures.