Serum cortisol (hydrocortisone) values in normal dogs as determined by radioimmunoassay

A radioimmunoassay method was utilized to determine serum cortisol (hydrocortisone) concentrations in normal dogs. The mean value was 2.32 mug/dl (minimum, 0.94; maximum, 3.70; with a coefficient of variation of 29.7%). Samples had been collected in the morning of the diurnal cycle. The cortisol antibody used was highly specific for cortisol and showed little cross reaction with other common physiologic corticosteroids, when they were assayed, using the radioimmunoassay procedure described.     

Augmented water binding and low cellular water content in erythrocytes of camel and camelids

We investigated a link between hemoglobin primary structure, hemoglobin hydrophobicity-hydrophilicity, and erythrocyte water content in various mammalian species. Some hemoglobin molecules, particularly those of the camel and camelids, contain more charged amino acid residues and are more hydrophilic than the hemoglobins of human and a number of other mammalian species. To test the in vivo significance of these alterations of hemoglobin primary structure, we determined the osmotically unresponsive erythrocyte water fractions in mannit solutions of various osmolarities at 4 degreesC. Among the species investigated, the size of the osmotically unresponsive erythrocyte water fraction relates in a positive linear way to hemoglobin hydrophilicity. The extreme low total erythrocyte water content of camel erythrocytes (1.1-1.3 g water/g dry mass) may be explained by a comparatively high osmotically unresponsive erythrocyte water fraction. It is proposed that alterations of hemoglobin sequences of camel and camelids may be the part of a natural selection process aimed at protecting these animals against osmotic dehydration in arid environments.