Publisher Summary Studies of the evolution of hemoglobin are largely based on amino acid sequence studies of mammalian blood and muscle hemoglobin. Only fragmentary structural data exist on only a few fish hemoglobin. Most of the times, metabolically active fish has such a large requirement for oxygen that blood transport hemoglobin is not only necessary, but even a slight anemia may be a serious disadvantage. Fish can solve their requirements for oxygen in many ways; the presence of special blood hemoglobin is only one link in a series of adaptations. This fact should be borne in mind when examining the oxygen transport properties of hemoglobin. Thus, oxygen transport depends upon the presence of gills, and/or lungs, their effective surface area, the distribution of capillaries, the rate of fluid pumping by the heart, the number of red blood cells, and the concentration of hemoglobin within them. For these reasons, it is necessary to consider not only the properties of the hemoglobin in free solution, but also their cellular environment and how this environment can modify the function of the hemoglobin.

6 Properties of Fish Hemoglobins

Gestation is a unique ephemeral physiologic state in that it is associated with significant but reversible alternations in many systems, including the endocrine and cardiovascular systems. During normal pregnancy, these endocrine and physiologic changes are essential for normal embryo/fetal development to ultimately produce viable offspring for the propagation of species. The current review addresses steroid (estrogen and progesterone) hormonal changes throughout gestation and compares them to systemic and uterine vascular physiologic adaptations to pregnancy. It must be stressed initially, that no true “cause and effect” relationship has been definitively established between production of steroid hormones in pregnancy and these vascular changes.

Maternal Cardiovascular and Other Physiologic Responses to the Endocrinology of Pregnancy

Regulation of oxygen affinity of mammalian haemoglobins.

Recent developments in prostaglandin biology have revealed diverse pharmacological activity (Ramwell and Rabinowitz, 1972), and although the specific physiological role of prostaglandins as intercellular or intracellular “hormones” is yet to be elucidated, most cells and tissues appear to have the capacity for both their evoked synthesis and release (Ramwell and Shaw, 1970) and their metabolism (Anggard and Samuelsson, 1964). The prostaglandins have many implications in hematology (Johnson and Ramwell, 1973a), and blood is a unique medium for their study since it contains single cell type components, each with a characteristic biological responsiveness but maintained in the same physiological environment.

The Mature Erythrocyte

Respiratory functions, buffer system, and electrolyte concentrations of blood during human pregnancy.

Causes of the postnatal decrease of blood oxygen affinity in lambs

Oxygen and carbon dioxide exchange across the cow placenta during the second part of pregnancy.

The influence of aldosterone and cortisol on oxygen affinity and cation concentration of the blood.

Triiodothyronine induced changes of oxygen affinity of blood

The oxygen affinity (expressed as oxygen half saturation pressure P 50 ), 2,3 diphosphoglycerate (2,3 DPG) concentration and other parameters were determined in the blood of lambs over a period of 60 days postnatally. The most pronounced decrease in oxygen affinity occurred during the first ten days of postnatal life, and it was found that this could be sufficiently explained by a combination of two factors, i.e. replacement of foetal with adult haemoglobin and decrease in erythrocyte pH. The blood of newborn lambs had a high concentration of 2,3 DPG (10.46 mM/L RBC), which decreased insignificantly during the first ten days of postnatal life and then dropped sharply between the tenth and twentieth post partum day, to reach the low adult level by the second month after birth. 2,3 DPG has no influence on the oxygen affinity of either foetal or adult sheep haemoglobin as demonstrated by experiments carried out with dialysed haemolysates of adult sheep and newborn lamb blood, where addition of 2,3 DPG did not alter the oxygen affinity of the dialysates.

A.M. Rathschlag-Schaefer

Papers

Causes of the postnatal decrease of blood oxygen affinity in lambs

Oxygen and carbon dioxide exchange across the cow placenta during the second part of pregnancy.

The influence of aldosterone and cortisol on oxygen affinity and cation concentration of the blood.

Triiodothyronine induced changes of oxygen affinity of blood

Causes of the postnatal decrease of blood oxygen affinity in lambs.