ABSTRACT
Actions and interactions of spontaneous diabetes mellitus (DM) and natural estrous cycles (sex seasons) on the regulation of serum monesterified fatty acids (NEFAs) and free glycerol (FG) levels in bitches in the fasting condition and during i.v. glucose (IVGTT) and insulin (ITT) tolerance tests, were studied. DM increased serum NEFAs concentration both in the basal condition and during IVGTT; it provoked a fall response to glucose load which is absent in normal controls. Estrous cycles did not modify these observations. Serum NEFAs levels during ITT were unresponsive in normal and diabetic bitches at every sex stage; flat, overlapped serum NEFAs profiles were then observed except for the diabetic group at A, which showed an early abrupt fall response of this variable from its high base line. DM increased also serum FG concentration in the fasting condition and during IVGTT. In the normal controls, serum FG base line was not affected by sex status; similary shaped, increasing, overlapped curves during the test were observed. In the diabetic bitches "in season" (either phase), serum FG basal value was hardly above in respect to anestrous, but during IVGTT their flat profiles coincided. DM increased serum FG concentration in the basal condition and during ITT, and modified the profiles of this variable. In normal dogs in the basal condition, serum FG concentration remained unaffected by sex status; this variable hard, transiently increased during ITT, which was not influenced by "sex seasons"; therefore, similarly shaped, overlapped serum FG profiles were then observed. In the normal and diabetic bitches, serum FG base line was not changed by "sex seasons". During ITT, serum FG mean profile in the diabetic bitches at EP was modestly above that observed in those at LP; differences for any other comparisions in normals or diabetic bitches were nonsignificant. As reported by us elsewhere, impaired glucose metabolism and absolute insulin dificiency induced ketose-prone, acidotic, insulin-dependent diabetic chryses in certain normal and diabetic beaches "in season" studied here. The unability of these animals for hydrolizingglyceride-glycerol via lipoproteinlipase (IVGTT) or via hormone sensitive fractions of lipase (ITT) and the abolished serum NEFAs suppressibility during modest hiperinsulinemia (ITT) appear to contribute to the production of such chryses...
Subject(s)
Dogs , Animals , Female , Diabetes Mellitus, Experimental/blood , Estrus/blood , Fatty Acids, Nonesterified/blood , Glycerol/blood , Analysis of Variance , Glucose Tolerance Test , InsulinABSTRACT
Conociendo que el bloqueo ß-adrenérgico con propranolol (P) puede provocar cuadros hipoglucémicos en pacientes diabéticos insulino-dependientes, hemos analizado la respuesta de algunas variables hormonales (insulina (I) y cortisol (C) séricos, adrenalina (A) y noradrenalina (NA) plasmáticas) y metabólicas (glucemia y ácidos grasos libres (AGL) séricos) a la administración de esta droga a perros machos por la vía oral (dosis: 80 mg, 3 veces por día, durante 10 días) (grupo A) o endovenosa (dosis: 1 mg/Kg a -30 min) (grupo B), estudiándose en estos últimos, el comportamiento de dichas variables durante la hipoglucemia insulinica (HI). Se controló la frecuencia cardíaca como índice del bloqueo. Se obtuvieron muestras de sangre en condiciones basales en los perros del grupo A, a 0 y 30 min., y en los del grupo B a -30 y o min., continuandose durante la HI cada 30 min. por 2 horas. En los animales con bloqueo crónico, el P no afectó los niveles de glucemia, I sérica y catecolaminas plasmáticas, pero redujo los de AGL y C séricos cuando se los comparó con los respectivos controles. Durante la HI (grupo B), el tratamiento con P no afectó el comportamiento de la glucemia o de la insulinemia, observándose descensos en los niveles de AGL (p < 0,001) y C (p < 0,05) séricos junto con un aumento de la repsuesta adrenalínica a la hipoglucemia, al compararlos con los de los perros no bloqueados. Los resultados expuestos indican que el mecanismo ß-adrenérgico no desempeña un papel importante en la recuperación de la HI