Acta physiologica latino americana最新文献

The involvement of the liver in the control of the renal excretion of water and sodium can be deduced from some recent investigations. Hypertonic or isotonic sodium chloride infusion into the hepatic portal vein enhanced renal sodium excretion when compared with identical infusions into a systemic vein. It has been suggested that a humoral factor produced by the liver could be a functional link between the liver and the kidney. In order to test this hypothesis, the present experiments were carried out in two groups of anesthetized dogs. Animals from group I were infused with NaCl (855 mmol/l) at a rate of 0.05 ml/min/kg b.w. during 30 min, into the portal vein. Blood samples were withdrawn from the suprahepatic vein, before (SH1) and coinciding with the maximal natriuresis after hypertonic saline infusion (SH2). Plasma from SH1 and SH2 were infused into the left renal artery (LRA) of dogs from group II. Two 20 min clearance periods were performed before and after each SH-infusion. After both SH-infusions urinary sodium excretion (UNaV) was significantly increased from preinfusion values in both kidneys, and these increases were significantly greater after SH2 than after SH1. No significant differences were found in UNaV between left and right kidney. After both plasma infusions the increases in urinary volume and osmolar clearance were higher in the infused than in the not infused kidney. These results suggest that the plasma leaving the liver contains a substance with natriuretic activity and that the infusion of hypertonic NaCl into the portal vein could induce either a higher secretion of the same substance or the presence of other different substance.

Chemical evidence is presented to demonstrate that short chain fatty acids selectively bind potassium instead of sodium in a simple lipid-water partition. The preference for potassium ions as measured by the K+/Na+ relationship increases from valeric acid (C5) to the higher members of the series, reaching a maximum at pelargonic acid (C9) under physiological conditions (37 C and potassium and sodium concentrations as in normal serum). Anions play a very important role in the selection of K+ ions. When NaHCO3, at the concentration present in normal serum, is added to the aqueous phase, a great increase in the absorption of K+ ions is observed, if compared with the same solution without NaHCO3 and at the same pH. A model is described as a working hypothesis which would explain the behavior of the fatty acids.

The composition of the volatile fatty acids emitted by Triatoma infestans of both sexes was studied. They were constituted by a mixture of the acids acetic, propionic, butyric, isobutyric, isovaleric, valeric and traces of isohexanoic and octanoic. Acetic acid was predominant followed by isobutyric and then by propionic acid. The other fatty acids are minor constituents. When acetic acid was discounted, the remaining composition was similar to the volatile fatty acid distribution pattern of Brindley gland. Both sexes showed a similar composition and therefore discard the possibility that they may function as sexual pheromones.

In the present paper the modification that BCG induces on experimental tumor growth and its possible human medical applications are analyzed. The mechanisms by which the BCG inoculated mixed with tumor cells enhance its rejection involve the participation of different cell populations, such as sensitized lymphocytes, activated macrophages and the spontaneous cytotoxicity effector cells (N. K. cells). The tumor rejection depends on the BCG doses and the inoculation modes. In this regard, high doses induce toxic effects and can activate suppressor mechanisms mediated by cells or serum factors. The action of BCG on tumoral growth is apparent only under certain circumstances where the host-tumor system should be carefully selected.

In isolated cat heart papillary muscle electrically driven, harmaline (HME) concentrations of 4.15 to 16.6 X 10(-5) M induced a dose dependent negative inotropic effect both at temperatures of 30 and 37 C. In fact, HME decreased both peak tension developed (PTD) and velocity of development of tension (dT/dt) and increased time to peak tension (TPT). The same concentrations induced also a dose-dependent increase of the effective refractory period (ERP). Concentrations of HME lower than 4.15 X 10(-5) M did not show any effect in papillary muscle. In isolated atria of the same cats either spontaneously beating or electrically driven, at 30 C, HME induced a dual inotropic effect. In fact, concentrations of 8.3 X 10(-5) M and 24.9 X 10(-5) M induced an increase in both PTD and dT/dt and lengthening of time to peak tension (TPT). Higher HME concentrations such as 41.5 X 10(-5) M induced a decrease in dT/dt, a negative inotropic effect, but still lengthened the TPT. In both preparations, whenever the dT/dt was depressed the PTD was diminished in spite of the prolongation of TPT. The lesser density of adrenergic innervation and catecholamines concentration in papillary muscle than in atrial myocardium probably explains the negative inotropic action of HME in ventricular myocardium as compared to the dual inotropic effect observed in atria.

Cell morphology, glutamic pyruvic (GTP) and glutamic oxalacetic transaminases (GOT) concentrations, and the ability to produce glucose or urea from different substrates (pyruvate, alanine, fructose, lactate and glutamine) were studied in isolated mouse and rat liver cells in the presence of Ca2+ and K+ chelating agents (0.1 M sodium perchlorate and 0.027 M sodium citrate with 1 mg/ml bovine albumin; ionic strength: 0.198, pH: 7.4). The chelating agent is perfused through the portal vein of an in situ liver, at low pressure (8 ml/min) at 20 C for 15 min. Cell dispersion is obtained by cutting liver lobes and "massaging" the tissue with a plastic spatula. Wash and cell concentration may be obtained by sedimentation or centrifugation in Krebs III, glucose 150 mg %, improved with 0.16 M pyruvate, 0.1 M fumarate and 0.16 M glutamate. This procedure furnished 53.06 +/- 3.33 X 10(6) cells, which was highly significant (p less than 0.001) with respect to saline controls: 6.11 +/- 1.91 X 10(6). After staining with Papanicolaou, hematoxylin-eosin, and PAS, the cellular material obtained was classified optically into: normal isolated parenchymal liver cells, hepatocyte clumps, "burst" cells, normal blood or reticuloendothelial cells, cellular debris and non-cellular material. Cell morphology showed that a constant perfusion (8 ml/min) with a minimal mechanical treatment, 82.5% of the liver cells appears normal. Biochemical study showed that transaminases are indeed lost, but this loss is below the amount capable of effecting metabolic blockade (3/4 of transaminases remain in liver cells; GOT in cells: 692 +/- 218; GPT in cells. 264 +/- 94; GOT in supernatant: 152 +/- 29; GPT in supernatant: 79 +/- 12 mUI/10(6) cells, after recovering 60 min at 37 C) (means +/- SEM). Conversion of substrates (sodium pyruvate 10 mM, 20 mM D-L alanine, 10 mM fructose and 20 mM D-L sodium lactate) into glucose was statistically significant with respect to the baseline when the liver cells were isolated and recovered (rat liver cells, basal: 25.37 +/- 3.73; pyruvate: 54.04 +/- 7.98; DL-alanine: 62 +/- 10.07; fructose: 264.67 +/- 20.51; DL-lactate: 78.05 +/- 17.99 mmoles/10(6) cels, means +/- SEM). Urea production from 5 mM DL-glutamine was statistically highly significant to the basal with rat liver cell isolated and recovered (basal: 160.60 +/- 3.76; DL-glutamine: 608.47 +/- 16.15 mmoles/10(6) cells; means +/- SEM). The results obtained suggest that liver cells isolated with Ca2+ and K+ chelating agents used as described above are of value for biochemical studies.

In the present work the effects of the hypophysis hormones on oviduct mucoprotein components distribution patterns were studied. Remarkable changes after treating the toad with hypophysis injections were apparent. The distribution pattern for hexose, sialic acid, hexosamine and phosphate from 18 hours hypophysis treated toads were found to be identical with those obtained from preovulatory period animals. On the other hand, the levels for mucoprotein components from hypophysis treated animals were found to be approximately one-half or more higher than those obtained from postovulatory period toads. Otherwise, hypophysis treatment of the toads in preovulatory period had not effect on the levels and distribution patterns of mucoprotein components. These results suggest that hypophysis hormones are involved in the increase of the oviduct secretory activity.