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The differential effects of KCl vs. KHCO3 for intravenous K+ repletion were evaluated in a series of nephrectomized dogs previously depleted of 20% of total-body K by a 2-wk regimen consisting of K-free diet plus DOCA plus chlorothiazide. Twenty-four percent of K losses (5% of original TBK) were replaced by a 2-h infusion of either CKl or KHCO3. Blood pH was maintained at normal levels by controlling the rate of respiration. Skeletal muscle biopsies were taken before and 2 h after repletion, and blood samples were taken at intervals throughout. The following differences resulting from KHCO3 compared to KCl repletion were found: a) a greater cellular K uptake, a lower rate of increase, and a lower steady-state extracellular K+ concentration; b) a less increase in intracellular K+ concentration and a less decrease in intracellular Na+ concentration. These differences, which were independent of extracellular pH or kidney function, are thought to be secondary to unequal distribution of Cl- and HCO3-ions.

Eight dogs were subjected to 80-90 percent coarctation of thoracic aorta, which produced a mean blood pressure gradient of 40 mmHg; six normal dogs were used as controls. Proximal aorta was compared with distal aorta, and carotid and femoral arteries removed after coarctation were compared against the contralateral vessels removed before coarctation. After 4 wk of coarctation, proximal aorta contained more total and intracellular Na (derived from 24Na fluxes and space measurements), more Mg, Cl, hydrolyzable SO4 equals to, and H2O than distal aorta. Hydrolyzable SO4 equals to was also higher in proximal than in distal noncoarcted aorta. Carotid arteries removed after coarctation had higher total and "noninulin" Na, higher Ca, and similar hydrolyzable SO4equals to and total hexosamine than the contralateral normal vessels. Aortic coarctation had no effect on ionic composition of femoral arteries. The data suggest that an increase in intravascular pressure has direct effects on vascular ionic composition. Although ionic changes may vary in different vessels, increased intracellular Na seems to be the most consistent finding.