ABSTRACT
La capacidad contráctil del útero puede ser evaluada in vitro por medio del método isométrico. El objetivo de este estudio fue comparar la efectividad de la administración simultánea de oxitocina e insulina en la contractilidad uterina. La comparación entre ambas hormonas se realizó en úteros aislados de 2 modelos experimentales: ratas hembras adultas en diferentes etapas del ciclo estral y ratas preñadas en fase final de preñez. Los úteros de estos animales fueron sometidos, in vitro, a la acción de dosis acumulativas de oxitocina (10-10 M a 10-8 M), insulina (200 mU/ml), y oxitocina más insulina. Los resultados obtenidos indican que in vitro la insulina no modificó significativamente la respuesta oxitócica. Sin embargo, la insulina aumentó la entrada de potasio al miometrio, medida como actividad de la Na-K ATPasa sensible a ouabaína. Este hallazgo indica efectividad de la insulina en el tejido uterino. Además es la primera demostración que insulina actúa en el miometrio en forma similar a lo descrito para el músculo esquelético. El efecto de insulina sobre la bomba de sodio indicaría que insulina no actuaría sinérgicamente con oxitocina
Subject(s)
Animals , Female , Pregnancy , Rats , Uterine Contraction , In Vitro Techniques , Insulin , Oxytocin , Uterine Contraction/physiology , Drug Therapy, Combination , Insulin , Myometrium , Oxytocin , Potassium , Sodium-Potassium-Exchanging ATPaseABSTRACT
Background: Sodium and potassium ions are involved in the regulation of blood pressure and the genesis of hypertension. Aim: to assess internal potassium balance, as a measure of sodium pump activity, in subjects with essential hypertension and diabetic patients. Patients and methods: Eleven hypertensive subject, 5 non-insulindependent diabetics and 16 age matched controls were studied. An acute oral load of 0.8 mEq/Kg body weight of KCI was administered and blood samples were drawn every 30 min thereafter, until 120 min, to measure plasma K+ levels. Urinary K+ excretion during this period was also measured. In eight hypertensive patients, the test was repeated after two week of supplentation with 60 mEq/day of KCI. The maximal increase in plasma potassium levels and the time required to achieve the maximum concentration was recorded. Results: All patients had normal serum creatinine levels. Mean fasting blood glucose of diabetic patients was 133 ñ 15.1 mg/dl. No difference between patients and controls in maximal increase plasma potassium increase, was observed. In hypertensive patients the lapse to achieve the maximal potassium concentration was longer than in controls. After the period of potassium supplementation in hypertensive patients, tbere was a significant increase in basal plasma K+ levels and the temporal pattern of plasma potassium increase was similar to that of controls. Between 63 and 68 percent of retained K+ load was translocated to the intracellular space at 120 min in all study groups. Conclusions: Internal potassium balance is not significantly altered in subjects with essential hypertension or in non-insulin-dependent diabetics