Acta physiologica Polonica最新文献

The formation of new adipocytes occurs either at the stage of multiplication or differentiation or both. It seems possible that the formation of new fat cells is dependent on the average cell weight in a given adipose tissue depot, but there may also be other regional, local regulatory factors. Multiplication of fat cells has been suggested to be stimulated by 17-beta-oestradiol while the differentiation of adipocytes is stimulated by growth hormone, glucocorticoids, insulin, insulin-like growth factor and female sex hormones. There are, probably, other factors acting in circulation or locally. The factors promoting growth of new fat cells with overfeeding are at present unknown. Some hypothetical possibilities are discussed.

Formation of acylenzyme complexes between the protein fraction isolated from pig thoracic aortas and palmitic, stearic, oleic, linoleic, linolenic and arachidic acid, was studied. The reaction brings about transformations of the periodically variable sinusoidal function of the enzyme absorbancy (energy level) depending on the kind of substrate utilized. Different changes in the enzyme energy level in the elementary process are induced by the saturated and polyunsaturated fatty acids and by oleic acid as demonstrated by the intermediate course of the function for oleylenzyme. The reaction rate constants were calculated and their negative curvilinear dependence upon molecular weight of the substrates has been shown. The differences in the acyl-enzyme reaction course and preferences are discussed with respect to the arterial metabolism and different accumulation of lipids.

The present study was designed to find out whether pressor responsiveness to vasopressin (AVP) is altered in spontaneously hypertensive rats (SHR) in comparison with their normotensive controls (WKY). Blood pressure and heart rate changes after injection of graded doses of 2.5, 5.0 and 10.0 ng of AVP (Calbiochem) i.v. were compared in 9 conscious, unrestrained spontaneously hypertensive (SHR) and 11 normotensive Wistar Kyoto (WKY) rats, chronically instrumented with venous and arterial catheters. The threshold dose necessary to elicit a significant increase in blood pressure and reduction of heart rate was lower in WKY than in SHR. At each dose level the blood pressure elevation persisted for a longer period in WKY than in SHR. Bradycardia was greater in WKY than in SHR both in absolute terms and in relation to the blood pressure increase. Thus, the results reveal diminished pressor responsiveness to moderate doses of AVP in SHR in spite of suppressed reflex bradycardia. It is suggested that the peripheral action of AVP on the vascular system is attenuated in SHR.

The binding sites for 125I-monoiododerivative of apamin in the central nervous system of rat, guinea-pig, chicken and frog were analysed and compared by computer assisted quantitative densitometric autoradiography on X-ray film. The highest level of binding sites in the rat and guinea-pig brain was found in the limbic-olfactory system and in the substantia gelatinosa of the spinal cord. In the chicken brain apamin binds preferentially to the tectum opticum and nuclei isthmi. In the frog brain no specific apamin binding sites were found. The role of presented topography for apamin binding sites is discussed in relation to neurotoxic properties of apamin.