Hematological changes in the newt during the process of splenic decongestion in reply to hypoxia

Abstract

Specimens of the newt, Triturus cristatus carnifex (Laurenti), anesthetized with chlorobutanol and exposed to humid air at 6° C for 300 min, accumulate about 50 of their red blood cells (RBC) in the spleen. When the newts are transferred to still water at 18° C, the spleen releases the RBC back into circulation, emptying itself out completely. This process counteracts the hypoxia caused by both the increase in temperature and low coefficient of oxygen diffusion in water. The analysis of the RBC counts, hematocrit value and percentage volumes of the spleen, blood and plasma (the last measured colorimetrically after injecting 0.05 ml of Evans blue in the conus arteriosus) in groups of newts sampled at various periods during the spleen decongestion reveals the trend of the compensatory process. The emptying out of the spleen takes less than an hour, causing significant increases in the RBC concentration after 15 and 30 min of immersion; the counts then undergo an inflexion which becomes significant at 120 min. The release of RBC into the blood stream causes an increase in blood volume which becomes statistically significant after 60 min, but reaches the value of the whole mass of the transferred RBC only after 120 min. The transfer of plasma during the compensatory process is the reason why the increases in RBC hematic concentration and in blood volume are not contemporary, as demonstrated by the significant decrease in plasma volume during spleen decongestion and by its increase (correlated to the decrease in RBC concentration) during the successive phases.

Blood and splenic respiratory compensation in larval newts

“…satory phenomena, identical to what has been observed in adults (Frangioni & Borgioli, 1989, 1993b. Cytologically, the MCV means of the larval erythrocytes (2463 ± 372 fl) are significantly lower (P < 0.01) than those reported in adults (2735 ± 280 fl) by Frangioni & Borgioli (1993a).…”

“…Adults of the Italian crested newt, Triturus carnifex (Laurenti), possess a physiological compensation mechanism involving the blood compartment by which they can regulate their oxygen supply: when the animals are in repose and well-oxygenated, the spleen accumulates up to 50% of the red blood cells (Frangioni & Borgioli, 1989, 1991a, 1993a, 1996, releasing them into circulation if the newts find themselves in a hypoxic environment, or with increased metabolic needs due to motor activity or a rise in temperature (Frangioni & Borgioli, 1991b, 1993b.…”

Haematological changes by splenic respiratory compensation in the cave salamander, Hydromantes genei

“…Farrel, 1991) report blood volume as a percentage of the body weight. In analogous conditions the crested newt's blood volume increases by 'only' 2.70% of its body weight (Frangioni & Borgioli, 1993~). The haemoconcentration encountered at 24 "C means that the circulating plasma is diminished by more than a third (34.69%, to be exact), given that this, as it is easy to calculate, is the percentage of plasma that must be eliminated from the blood in order to raise the haematocrit value from 12.05 to 18.15.…”

“…As the spleen appears completely empty at 18 "C, the erythrocytes with which it was packed at 6 "C must obviously have been put into circulation; however, the haematological parameters at the two temperatures are practically identical, despite the quantity of erythrocytes emptied into the bloodstream, a mass equal to 0.55% of the body weight (amount obtained from the difference between the percentage weights of the spleens at the two temperatures: 0.80 minus 0.25). This means that when the organ empties its red blood cells into the bloodstream there is a parallel increase in the circulating plasma (presumably thanks to the increased activity of the hearts of the lymphatic system, particularly large in all amphibians), so that the volume of blood increases but not the proportion between its two components, just as happens in the crested newt (Frangioni & Borgioli, 1993~).…”

Storage of Blood in the Mammalian Spleen: an Evolutionary Perspective

“…In Chelonia, Ophidia, and Anura, the need for an increase of blood oxygen carrying capacity is satisfied by increasing the hematocrit through reduction of the plasma volume, with no contribution of the spleen (Lillywhite and Smits 1984;Smits and Kozubowski 1985;Malvin et al 1995). On the other hand, a group of researchers indicated that in Urodela erythrocytes are poured into the blood stream in reply to hypoxia (Frangioni and Borgioli 1993). Moreover, in Crocodilia, prolonged hypothermia caused erythrocytes sequestration in the spleen (Huggins and Percoco 1965), while hibernation did not cause blood storage in the spleens of Anura (Cooper et al 1992) and Iguanidae (Tracy and Diamond 2005).…”