A STUDY ON REGULATING FACTORS OF PLASMA REFILLING DURING HEMODIALYSIS

Hypotension is frequently encountered during hemodialysis (HD). One of the main factors of the HD-induced hypotension is acute reduction of circulating plasma volume by water removal, which is induced by the po or plasma refilling from the extravascular space into vessels. The det erminants of plasma refilling, however, have not been clearly identifi ed. Recently, we devised a mathematical model of water transport in HD patients, which can estimate the plasma-refilling coefficient (Kr) du ring HD. In the present study, we evaluated the factors determining pl asma refilling by using this model. In 13 patients undergoing regular HD, the changes of Kr during HD were calculated from the model. Levels of ANP, cGMP, cAMP, endothelin, angiotensin II and vasopressin were m easured before and after HD. Kr fell from 750.4 +/- 558.0 to 112.8 +/- 81.9 ml/mm Hg/h during HD. The rate of water removal during HD showed no significant correlation with the changes of Kr. Among the hormones and nucleotides measured here, plasma ANP level and cGMP were signifi cantly correlated with Kr (r = 0.78, p < 0.01 and r = 0.62, p < 0.01, respectively). Our findings suggest that severe reduction in the level of serum ANP during HD, which is induced by water removal, plays some role in HD-induced hypotension through the attenuation of plasma refi lling in HD patients.