No abstract

Two sizes of microsphere were used to determine regional blood flow in pregnant guinea-pigs. Tissue perfusion measured with 50 micron microspheres was significantly greater than that measured with 15 micron microspheres in the small intestine, uterus, vagina, and placenta. A significantly larger proportion of the smaller microspheres passed through the systemic vasculature and could be detected in the lungs.

Nα‐triglycyl‐(8‐lysine)‐vasopressin (TGLVP) was administered intravenously to pregnant guinea pigs and the effect on regional blood flow examined by the radioactive microsphere technique. A dose of 10 μg/kg TGLVP caused an elevation of the mean arterial blood pressure, from 6.4 to 11.1 kPa, a significant reduction in blood flow to the gut, skin and skeletal muscle and a significant increase in blood flow to the spleen. The number of 15 ± 5 μm microspheres reaching the lungs diminished significantly after 10 μg/kg TGLVP, indicating that this dose constricted arterio‐venous short circuits in the systemic circulation. There was also a decrease in blood flow to the urogenital tract, including the placentae. When 3 μg/kg TGLVP was injected, the mean arterial blood pressure rose from 6.5 to 8.7 kPa and there was no longer any consistent effect on maternal placental blood flow. It is suggested that pregnancy constitutes a contraindication for TGLVP, since a reduction in uterine and maternal placental blood flow might occur with clinically relevant doses.

In most models of capillary gas exchange, the binding curves for O2 and CO2 are represented by simple analytical expressions, and the interactions among the haemoglobin ligands are either neglected or are assigned fixed values independent of PO2, PCO2, pH and red cell DPG. We here present algorithms and a computer program in which the binding curves are described in a near-rigorous manner. This enables solution of a set of typical equations for a unit of blood which undergoes gaseous and proton exchange. We have applied the algorithms to the problem of calculating pulmonary blood flow from the gaseous exchange in the lung by the single-breath method of Kim et al. (1966), where the CO2 binding curves of arterial and mixed venous blood are approximated by straight lines. The application of the algorithms shows that this approximation introduces significant errors in the calculated pulmonary blood flow.

Na‐triglycyl‐(8‐lysine)‐vasopressin (TGLVP) was administered intravenously to pregnant guinea pigs and the effect on regional blood flow examined by the radioactive microsphere technique. A dose of 10 μg/kg TGLVP caused an elevation of the mean arterial blood pressure, from 6.4 to 11.1 kPa, a significant reduction in blood flow to the gut, skin and skeletal muscle and a significant increase in blood flow to the spleen. The number of 15 ± 5 urn microspheres reaching the lungs diminished significantly after 10 μg/kg TGLVP, indicating that this dose constricted arterio‐venous short circuits in the systemic circulation. There was also a decrease in blood flow to the urogenital tract, including the placentae. When 3 μg/kg TGLVP was injected, the mean arterial blood pressure rose from 6.5 to 8.7 kPa and there was no longer any consistent effect on maternal placental blood flow. It is suggested that pregnancy constitutes a contraindication for TGLVP, since a reduction in uterine and maternal placental blood flow might occur with clinically relevant doses.