sodium-cyanate and Hypertension--Pulmonary

Three weeks of sodium cyanate (NaCNO) intraperitoneal treatment in rats (n = 15) induced high hemoglobin O2 affinity, i.e., low PO2 at 50% hemoglobin saturation (P50), 20.5 +/- 1.4 Torr, in comparison with the mean control values, 34.5 +/- 1.6 Torr (n = 15). NaCNO rats showed a reduction in mean body weight, 376 +/- 27 g, in comparison with controls, 423 +/- 23 g (P less than 0.001). Despite arterial O2 partial pressure (PaO2) within normal limits NaCNO-treated rats had a higher systolic right ventricular pressure (SRVP), 33.7 +/- 3.1 Torr, in comparison with control value, 29.0 +/- 2.5 Torr (P less than 0.001). Right ventricle weights were significantly increased (P less than 0.001). After 60 min of an hypoxic challenge (fractional concentration of inspired O2 = 0.10) NaCNO-treated rats increased SRVP of only 7 +/- 4% compared with 46 +/- 9% in the control animals. Inducing high hemoglobin affinity in rats (n = 10; 6 wk NaCNO treatment) resulted in increases in hematocrit ratio and hemoglobin concentration (P less than 0.001). The characteristics of the red blood cell (RBC) itself changed; values of mean cell volume, mean cell hemoglobin, and mean cell hemoglobin concentration being significantly increased (P less than 0.001) when compared with mean control values. The count of nucleated RBC's appeared to be significantly higher from the 2nd wk of NaCNO treatment. Chronic NaCNO treatment was demonstrated to exert "hypoxia-like" effects since it induced prevention of normal growth, polycythemia, pulmonary hypertension, right ventricular hypertrophy, and blunted pulmonary pressor response to acute hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Chronic Disease; Cyanates; Erythrocyte Indices; Hemoglobins; Hypertension, Pulmonary; Hypoxia; Oxygen; Pulmonary Circulation; Rats; Vascular Resistance