In recent dog studies, intrapericardial injection of Freund's adjuvant resulted in sodium retention, pulmonary edema, liver congestion, and ascites. Twenty-two experiments were initiated 6–13 days after pericardial injection. Micropuncture and clearance measurements were made during chronic cardiac tamponade (CCT) and 60 min after pericardiocentesis (PC). Following PC, sodium excretion (UNaV) increased from 12.2 to 41.3 μequiv./min. Glomerular filtration rate (GFR) during CCT was unaltered (from 37.3 to 38.7 mL/min) by PC. Single nephron glomerular filtration rate (sngfr) increased 23% (p < 0.005). Proximal fractional reabsorption (FR) decreased 6% after PC. Kidney filtration fraction (FF) increased from 0.35 to 0.38 (p < 0.01). Superficial nephron FF (six dogs) increased from 0.25 to 0.32 (p < 0.02). Peritubular capillary protein concentrations decreased following PC (from 7.41 to 6.89 g/100 mL), a result of decreasing systemic protein concentrations (from 5.51 to 4.69 g/100 mL). Tubule and capillary hydrostatic pressures (another six dogs) increased 6.2 and 3.3 mmHg, respectively, following PC (p < 0.05 and p < 0.005). The results indicate PC causes increased UNaV. GFR did not appear to influence UNaV. Decreased FR in the proximal tubule is secondary to increased sngfr, absolute absorption (C) remaining unaltered. The behaviour of C is in part explained by diminished capillary oncotic pressure and increased capillary hydraulic pressure.
A progression in peritubular capillary flow reduction and tubulointerstitial fibrosis reflected by FE Mg predict the decline in glomerular filtration rate