Effect of age and sex in renal function by ultrasound and serum chemistry in two primate species (Alouatta caraya and Sapajus apella)

Background Comparative studies of kidney morphophysiology in nonhuman primates can help us investigate interspecies differences in growth and aging patterns. Methods We tested the effect of age and sex in renal morphophysiology in 21 Alouatta caraya and 21 Sapajus apella (age range = 0.5-26 years) by ultrasound, red blood cell (RBC) count, and kidney function tests. Results A. caraya had greater growth rate and absolute renal volume than S. apella, but the latter showed a greater relative renal volume and RBC count. There was a negative relationship between RBC and age, a positive relationship between creatinine and body mass, and an apparent negative relationship between creatinine and age only in S. apella. Conclusions Our results indicate that A. caraya has a faster aging mechanism than S. apella, and the higher relative kidney volume in S. apella is suggestive of high metabolic demands in this species.