Compensatory Renal Growth in the Mouse. I. Allometric Approach to the Effect of Age

Abstract

SummaryAllometry, defined as the relationship between the growth rates of organs to the weight of the whole body (38), was used to study the effect of age on the degree of compensatory renal growth (CRG) in the mouse. The normal growth of the kidneys relative to body weight (BW) was determined in animals between 5 to 50 days of age. In one group, nephrectomy and sham operations were performed at 5, 15, and 35 days of age. The remaining ("renoprival") kidney was removed 15 days postnephrectomy. In a second group, nephrectomy was performed on 5-day-old animals, the renoprival kidney being removed after 30 or 45 days. Regression equations were calculated by least-squares after logarithmic transformation and different groups were compared by analysis of covariance. The regression equation for the control kidney was kidney weight (KW) = 0.0093 BW0.86 (r = 0.96). The regression for renoprival kidneys in females was KW = 0.0142 BwO.'~ (r = O.%) after 15 days and, in comparison, was not significantly different after 30 to 45 days. The intrval between control and renoprival regressions was equivalent to a difference of 243% KW. In male mice, the regression for renoprival kidneys after 15 days was KW = 0.0103 BW0.96 (r = 0.98) and was not significantly different after 30 to 45 days. This study suggests that in young mice the time required for complete CRG may be a maximum of 15 days and that the amount of CRG does not depend on the age at operation. After CRG, a new equilibrium is reached which is therafter maintained up to a minimum of 50 days of age.

Influence of Age on Compensatory Renal Growth in Rats

“…The relative increase in kidney weight was much less pronounced in adult than in young animals. This observation corroborates previous findings in young and adult rats ( 1-4, 10, 12) dogs (23), and guinea-pigs (22) but does not accord with a study in growing mice (13). It is possible that the controversial findings are due to differences in species.…”

Compensatory Renal Growth in the Mouse. II. The Effect of Growth Hormone Deficiency

“…The allometric relationships for the right kidney and for the total renal mass in the lit/lit mouse are very similar to those of the heterozygote control (25). The slope of the right KW regression is slightly greater in the lit/lit (0.93) than in the lit/+ (-0.86), but the general form is the same.…”

“…The growth of the renoprival kidney in the lit/lit animal is similar to that in the normal mouse. The renoprival kidney is 40% heavier than controls, compared with 43% in the lit/+ mouse (25). This suggests that the mechanism controlling renal size is not affected by GH deficiency which is responsible for the smaller dimensions of the lit/lit mouse.…”

Relationships Between Organ Weight and Body/Brain Weight in the Rat: What Is the Best Analytical Endpoint?

“…This potential for error in evaluating the effects of chemicals on the weights of adrenal glands and other organs has been reported in many previous reports (Angervall and Carlström, 1963;Setnikar and Magistretti, 1965;Krames and Van Liere, 1966;Dikstein et al, 1967;Feron et al, 1973;Stevens, 1976Stevens, , 1977Trieb et al, 1976;Schärer, 1977;Shirley, 1977Shirley, , 1982Takizawa, 1978;Hutson et al, 1981; TOXICOLOGIC PATHOLOGY Uemitsu et al, 1984;Brown et al, 1985;Salsburg, 1986;Famula et al, 1988). In the cases where the organ-to-body weight relationship does not justify the analysis of ratio values, several alternative methods have been suggested.…”

“…32, No. 4, 2004 OPTIMAL ORGAN WEIGHT ANALYSES 461 FIGURE 6.-Continued complications associated with use of absolute weights or relative weights (Dikstein et al, 1967;Spencer, 1968;Simpson and Spears, 1973;Stevens, 1976Stevens, , 1977Trieb et al, 1976;Hutson et al, 1981), however none of these have been widely used to date. The results of this evaluation are summarized in Table 3.…”