Estereología renal en el cobayo (Cavia porcellus) / Renal stereology in the guinea pig (Cavia porcellus)

El cobayo (Cavia porcellus) es un roedor perteneciente al Orden Rodentia y a la Familia Caviidae, utilizado como animal de laboratorio y de consumo humano. Los parámetros cuantitativos del riñón entregan importante información de su morfofunción dada su labor en la homeostasis del organismo. El objetivo de este estudio fue describir el riñón de cobayo (Cavia porcellus), analizando las características estereológicas para futuros estudios experimentales. Se utilizaron 5 cobayos machos, obtenidos del Bioterio de la Universidad de La Frontera, Temuco, Chile. El riñón de cobayo pesó 3,2 g, aproximadamente. El riñón posee 140.298 glomérulos en total, Nv de 458 mm³, Vv de 7,89% y Sv de 3,58 mm²/ mm³. El volumen glomerular del riñón fue de 1,73 x 10(4)mm³ y el diámetro glomerular de 90 jm. Factores como especie, edad, peso corporal, peso y volumen renal, son importantes a considerar, ya que diferencian los resultados en investigaciones morfofuncionales.

The guinea pig, (Cavia porcellus) is a rodent pertaining to the Rodentia group and the Caviidae family, used as a laboratory animal and for human consumption. Quantitative parameters of the kidney provides important information of its morphofunction, given its labor in the organism's homeostasis. The aim or this study was to describe the kidney of the guinea pig (Cavia porcellus), analyzing the stereological characteristics for future experimental studies. Five male guinea pigs (Cavia porcellus) obtained from the Biotery of the Universidad de la Frontera, Temuco, Chile, were used. The kidney of the guinea pig weighed approximately 3.2g. The kidney has 140,298 total glomerulus, Nv of 458 mm³, Vv of 7.89% and Svof 3.58mm²/mm³. The glomerular volume of the kidney was of 1.73 x 10(4)mm³ and a glomerular diameter of 90 urn. Factors such as species, age, body weight and renal volume, are important to consider, as they differentiate the results in the morphofunctional investigations.

Mechanisms of hyperkalemia associated with hyporeninemic hypoaldosteronism in streptozotocin-induced diabetic rats

This study was aimed at investigating the mechanisms of clinically important overt hyperkalemia in diabetes mellitus with underlying hyporeninemic hypoaldosteronism known as a classic model of the syndrome of hyporeninemic hypoaldosteronism (SHH). Rats (Sprague-Dawley, male) were streptozotocin-treated (60 mg/kg, ip) and used after 60 days. Rats with plasma glucose levels higher than 300 mg/dL (mean +/- SEM, 423 +/- 20 mg/dL, n = 8) were selected as the diabetic group. Age-matched normal rats served as control (mean plasma glucose, 88 +/- 2, mg/dL, n = 8). Serum potassium concentrations and osmolalities as well as serum creatinine levels were significantly higher in the diabetic than in the control group (5.07 +/- 0.09 vs. 4.68 +/- 0.11 mEq/L; 330 +/- 14 vs 290 +/- 3 mOsm/L; 0.40 +/- 0.03 vs 0.31 +/- 0.02 mg/dL, p < 0.05). Plasma renin activity (PRA) in the diabetic group was significantly lower than that in the control group (6.0 +/- 1.0 vs 12.1 +/- 1.1 ng Al/ml/h, p < 0.001). Plasma aldosterone concentration (PAC) was also significantly lower in the former than in the latter (368 +/- 30 vs 761 +/- 57 pg/ml, p < 0.001). Renomegaly, abnormal distal tubular cells with few organelles, and increased lipid droplets with pyknotic nucleus in zona glomerulosa of the adrenal glands were noted in the diabetic group. In conclusion, multifactorial causes including insulinopenia, hyperosmolality, elevated serum creatinine level and hypoaldosteronism with possible contribution of altered distal tubular response to aldosterone may have interacted to develop hyperkalemia in these diabetic rats.