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R R Rodríguez

Publications and source records attributed to R R Rodríguez.

41 records · Page 3Linked to original sources
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Effect of estrogens on blood sugar, serum insulin and serum free fatty acids, and pancreas cytology in female dogs.

We analyzed the changes in blood sugar (BS), serum immunoreactive insulin (IRI), circulating free fatty acids (FFA) and pancreatic cytology caused by estrogenization at low pharmacological dosage in female dogs. Vehicle-injected and untreated controls (anestrus) were studied as well. Neither mean basal BS nor basal serum IRI was modified by the treatments, while the mean basal serum FFA value was raised. Glucose tolerance was not modified by the estrogens while glucose y-mean was significantly raised. Hyperglycemia was higher for a longer time in estrogenized animals compared to both controls, while the profiles of hyperinsulinemia coincided. In the estrogen-treated bitches, the pancreatic B-cells contained scarse brown-stained granules near their vascular pole, as shown by an immunochemical method. In the peripheral part of the pancreas, near the acini, some solitary, poorly beta-granulated B-cells were present. During the IVGTT, serum FFA reached lower values for a longer time in the estrogenized bitches as compared to those found in both control groups. Insulin-induced hypoglycemia in the estrogenized animals coincided with the one evoked in the vehicle controls; in the semilog relationship of serum IRI and time, y-mean was lower than that observed in oil-injected controls, and insulin space was larger. The serum FFA levels of these estrogenized bitches, very high in the basal conditions, did not respond to insulin administration, and were above those found in untreated controls and also in vehicle-injected controls just at the beginning of the test. These results are discussed. We came to the conclusion that estrogenization causes some glucose intolerance in bitches while insulin sensitivity remains normal in the IVITT as studied measuring BS. The glucose intolerance is thought to be related to a reduction in glucose space and occurs despite the normality of the serum IRI response. The pancreas must have an intense secretory response in vivo as as to maintain normal IRI activity despite degranulation of the islets of Langerhans and poor islet hypertrophy and neoformation. The serum FFA changes are thought to contribute towards the tendency to adiposity in these animals.

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Effects of short-term thyroxine treatment on pancreatic cytology and responses of blood sugar, serum insulin and serum free fatty acids to epinephrine infusion.

The influence of short-term treatment with l-thyroxine on pancreatic histology and on the responses of glycemia, insulinemia and serum free fatty acids to a continuous l-epinephrine infusion in the absence or presence of alpha- and beta-adrenergic blockade was studied in male dogs. l-Epinephrine dosage: 0.06 microgram/kg body weight/min for 55 min. Two experimental groups were studied, one treated for 10 days with sodium l-thyroxine, one daily dose of 100 micrograms/kg body weight, the other of untreated controls. Three alternative treatments were applied to dogs of both groups: 1) no treatment; 2) alpha-adrenergic blockade with phentolamine (2.0 mg/kg body weight, 35 min before starting the l-epinephrine infusion); 3) beta-adrenergic blockade with propranolol (0.3 mg/kg body weight, 20 min before starting the l-epinephrine infusion). Body weight, rectal temperature, heart and respiratory rates were used as guidelines to assess experimental hyperthyroidism. Insulin immunocytolocalization was also studied in the Langerhans islets of T4-treated and control dogs. Body weight decreased and rectal temperature did not vary as a result of thyroxine administration which had no significant effect on respiratory and heart rate. The mean number of breaths from 0 to 120 min from the start of l-epinephrine infusion decreased in both T4-treated and control dogs submitted to propranolol blockage compared to non-blocked animals; phentolamine had no effect on the respiratory rate. Thyroxine treatment did not modify the number of heart beats, but phentolamine blockade had a different effect in T4-treated compared to control dogs whereas propranolol had similar effects in these two groups. Histological examination of the Langerhans islets of dogs submitted to short-term thyroxine treatment showed degranulation though no vacuolation. Most of the beta-granules contained in the B-cells of these islets were found near the cell membrane, thus forming a dark brown line after the immunochemical reaction. Since negative images of B-cell nuclei and vascular spaces were predominant in these specimens, the pancreas of T4-treated dogs presented a mesh structure. In dogs submitted to short-term thyroxine treatment, the hyperglycemic response to l-epinephrine was enhanced and prolonged as compared to untreated controls. In normal dogs, this response is mainly mediated by alpha-adrenergic receptors while beta-receptors hardly influence this response.(ABSTRACT TRUNCATED AT 400 WORDS)

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