No abstract

SummaryHeart blood pools were evaluated by different indicator dilution models from single detector 113mIn radiocardiographic measurements on healthy subjects. It appeared that generally accepted mathematical expressions based on the nth moments of the radiocardiographic dilution curve overestimate the heart volumes by 30–40%. The study suggests that the indicator dispersion within the heart chambers is an dilution process, which ought to be included in the radiocardiographic models. Dispersion models based on the random walk equation, probability density function and the gamma variate model produced consistent heart volumes. The suitability of the dispersion models for clinical routine use is discussed briefly.

A comparative study was performed on the plasma 11-hydroxycorticosteroids (11-OHCS) responses to lysine-8-vasopressin (LVP) before and during ingestion of an oral contraceptive wieh oestrogenic activity. A total of 19 healthy women with a normal menstrual cycle and normal plasma 11-OHCS content in blood samples at 8 a.m. and 4 p.m. were included in the study. The results show that the mean response of plasma 11-OHCS to the administration of LVP was equal in magnitude before and during ingestion of the contraceptive, although the baseline value of 11-OHCS doubled as a result of the treatment. On the other hand, during contraceptive treatment the increase of plasma 11-OHCS concentration after the administration of LVP was somewhat slower, reaching its peak later than before treatment. The noticeable variation in individual responses of plasma 11-OHCS to LVP increased during the treatment. Three subjects showed weak responses to LVP, although the adrenocortical responses to exogenous ACTH were quite normal. The inidvidual responses to LVP before and during ingestion of an oral contraceptive with oestrogenic activity are discussed.