Kidney concentrating ability of a subterranean xeric rodent, the naked mole-rat (Heterocephalus glaber)

Abstract

The naked mole-rat (Heterocephalus glaber) is a strictly subterranean mammal inhabiting the arid zones of north-east Africa. These animals have no access to free water and water balance thus might be facilitated by regulating renal water loss. The urinary concentrating ability of the naked mole-rat was determined using five dietary manipulations in which both water and salt content were altered. "Control" animals (n = 7) received a high quality protein cereal mixed to a thin paste with water (1 g cereal: 8.5 g water). Water stress was induced by reducing the water content of the diet by either 50% (n = 7) or 65% (n = 7). Salt loading was facilitated by replacing the water with the same volume of either 0.9% salt (n = 7) or 3.0% salt (n = 4) solutions. Changes in body mass, food consumption and urine volume were measured daily. The effect of diet on osmolality and electrolyte concentrations of urine and plasma were determined on termination of the diet trials. Although energy intake was not reduced, naked mole-rats lost body weight with both water stress treatments. Urine volume voided per day decreased significantly with both water stress treatments (P < 0.05), such that the most extreme water stress led to an 80% reduction in urine volume. Mildly salt-loaded animals gained weight, yet underwent a sodium diuresis, as indicated by a 1.3-fold increase in the daily volume of urine voided (P < 0.05). Maximum urine concentration (1521 +/- 250 mmol.kg-1) was achieved with mild water stress and was 4.6 +/- 0.9 times that of plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential osmoregulatory capabilities of common spiny mice (Acomys cahirinus) from adjacent microhabitats

“…This resulted in significant decreases of [K + ], [Cl − ] and urea. An increase in urine volume with a corresponding decrease in urine osmolality was also observed in the mink Mustela vison (Eriksson, Valtonen & Makela, 1984) and naked mole rat Heterocephalus glaber (Urison & Buffenstein, 1994) for similar conditions (increasing water salt concentrations from 0.9% to 3.0% and from 0.5% to 2%, respectively). This does not, however, explain the observed differences between offspring and founders.…”

Vascular aging in the longest-living rodent, the naked mole rat

“…Young (Ͻ2 yr old; n ϭ 8) and ϳ12-yr-old (n ϭ 6; which is the oldest currently available age-group in this species) NMRs (weighing 25-38 g) were from the well-characterized colonies maintained in Dr. Buffenstein's laboratory at City College of New York (CCNY) (3,6,30,33,38). In addition, tissue samples harvested from 26-yr-old NMRs were also used in biochemical aspects of this study.…”

Is the distribution of the arid‐occurring otomyine rodents of southern Africa related to physiological adaptation or refuge type?

“…Heterocephalus glaber, 1521 mOsmol −1 : Urison & Buffenstein, 1994; Neotoma lepida, 2567 mOsmol −1 : Lee, 1963; Xerus inauris, 3280 mOsmol −1 : Marsh, Louw & Berry 1978). The maximum urine concentrating ability of O. unisulcatus seems to be slightly higher than for these herbivores, while that of P. littledalei is similar to the high concentrating ability of granivorous species such as Dipodomys merriami (Carpenter, 1966) and Gerbillus gerbillus (MacMillen & Lee, 1967), suggesting some adaptation of their renal function to aridity.…”