AN INCREASE IN MICROPULMONARY RED-CELL MASS IN HYPERLIPIDEMIC PATIENTS

It is known that pulmonary microcirculation theology is partly affecte d by plasma levels of lipoproteins, but only a few data are available for humans. Therefore, in a sample of 30 normal volunteers and 90 pati ents with various types of primary hyperlipoproteinaemia, the plasma l evels of total cholesterol (Chol), low density cholesterol (LDL), the high density cholesterol(HDL), triglyceride (Tg) and fibrinogen (Fib) were measured in conjunction with determinations of plasma viscosity ( PV) and the pulmonary capillary red cell volume (RCV(c)). RCV(c) was e stimated from measurements of the vascular component of the single-bre ath-diffusing lung capacity for carbon monoxide, using our own modific ation of the Roughton-Forster's method. By stepwise regression analysi s, the variation in RCV, was almost completely accounted for (r(2) = 0 .87) by variations in PV, Chol, Tg and the anthropometric confounding factors. The proposed explanations for increased pulmonary capillary r ed cell mass (up to 151% of the predicted value) in hyperlipidaemic pa tients included the hypothesis of increased pulmonary microhaematocrit , which agrees with the observed in-vitro lipoprotein-dependent increa se in erythrocyte aggregability.