Acta physiologica Academiae Scientiarum Hungaricae最新文献

Amniotic fluid was collected from women in the 2nd trimester of their gravidity by amniocentesis and its effect on the isolated pregnant rat uterine preparation investigated. It was demonstrated that some of the amniotic fluid components partially purified by using the combination of various separation techniques stimulated, while others inhibited the contractions of the isolated rat uterine preparation. The inhibitory component, called utero-inhibin also inhibited the spontaneous contractions as well as the basal tone of the isolated rat intestinal preparation and those of the isolated human pregnant myometrium preparation. It is speculated that the inhibitory factor might play a physiological role in maintaining the resting state of human uterus during pregnancy.

The effect of mazindol on feeding behaviour was investigated in rats fasted for 24 hours. They were then given mazindol i.p. and placed in a new environment. The effect of the drug on the disappearance of 3H-noradrenaline (3H-NA) from various parts of the brain after injection into the cerebral ventricles was also investigated. Mazindol was more potent in suppressing feeding behaviour than in reducing food intake, indicating that a number of aspects of feeding behaviour may be more sensitive indices of the anorectic effect of a drug than food intake per se. Mazindol, in a dose of 30 mg/kg, accelerated the disappearance of 3H-NA from the medial hypothalamus but not from other areas of the brain, suggesting that the drug has a locus-specific action on cerebral noradrenaline metabolism.

Following stimulation with NaCl of different concentrations, responses from one, two or three receptor cells of the sensillae could be recorded, one of them being always "dominant". The other one or two secondary cells showed a lower frequency and a faster adaptation. The responses of the dominant cells proved to be variable, even to repeated stimulations using the same concentration of the same substance. Increasing the concentration from 0.01 mol/l to 1.0 mol/l, the initial frequency may increase or decrease, however, frequency minimum or maximum may also occur at an intermediate concentration. These findings indicate a less specialized stage of the receptor cells. The individual characteristics of the receptor cells may be surpassed when averaging the responses of sufficiently high number of cells.

The effects of lithocholic acid (LCA), chenodeoxycholic acid (CDCA), deoxycholic acid (DOCA), cholic acid (CA) and dehydrocholic acid (DHCA) on the biliary excretion of amaranth (AM) in rats and on the respiration of isolated liver mitochondria were investigated. Bile acids diminished the biliary excretion of AM, and in vitro they enhanced the state 4 mitochondrial respiration and inhibited DNP- and ADP-stimulated oxygen consumption. The ID50 values (mumol/kg i.v.) and I50 concentrations (X 10(-5) M) of the bile acids for inhibiting AM excretion and ADP-stimulated mitochondrial respiration, respectively, were as follows: for LCA 16 and 3.3, for CDCA 160 and 24, for DOCA 230 and 31, for CA 680 and 105, and for DHCA 700 and 260. LCA, CDCA and DOCA inhibited the biliary excretion of AM uncompetitively. It is concluded that the toxic effect of LCA, CDCA and DOCA on mitochondria might play a role in their inhibitory action on the biliary transport of AM.

The possibility of local recording of the electrical activity of the sinus node was investigated on 22 dogs. Using a small unipolar electrode positioned at the proximity of the sinus node and applying a 2-4-fold electric amplification, an early, slow and low-amplitude wave could be recorded 20-40 ms before the P wave. This early wave gradually decreased when the electrode was moved away from the sinus node and finally fused into the local P wave. Temporary arrest of sinus node activity by injection of adenosine into the sinus node artery, electrical stimulation of the vagal nerve by infiltration with phenol of the sinus node region made the local P wave to disappear. Similarly, no early action before the P wave could be seen if the sinus node was driven electrically. The early wave recorded in the proximity of the sinus node represents the depolarization of the sinus node, and it is suitable to study the pacemaker activity of the sinus node together with sinoauricular conduction.

In acute immobilized rats, the effect on the EEG of thermal and chemical (capsaicin microinjection) stimulation of the warm sensors in the preoptic region, mid-hypothalamic area and posterior hypothalamus were studied. Both localized heating and capsaicin resulted in a sleep-like EEG with spindles and slow waves. Stimulation of the posterior hypothalamus was the most effective and stimulation in the mid-hypothalamus was the least effective in inducing spindle activity. Since capsaicin is regarded as a specific stimulant for the hypothalamic warm sensors, the results suggest that the EEG effect, and probably the sleep-inducing effect, of heat are mediated via the central thermoreceptors, and cannot be due to a non-specific activation of the basal forebrain hypnogenic mechanisms.

The effect of native serum samples from schizophrenic and control patients on the electrically induced contractions of the isolated mouse vas deferens (MVD) preparations was investigated. It was demonstrated that only the samples of schizophrenic origin elicited a naloxone dependent inhibition on the contractions of the MVD preparations, while sera from healthy individuals and those from non schizophrenic but mentally ill patients proved to be ineffective in this respect. By using ultrafiltration and gel chromatographic techniques, four fractions disclosing MVD related biological activity could be separated from schizophrenic samples. Chemical analysis revealed an elevated quantity of ninhydrin and Lowry positive materials as well as of unidentified carbohydrate components in the active fractions. Molecular mass of the serum ingredients carrying opioid activity was found to range between 0.5 and 5.0 KD. It is speculated that new appearance or the accumulation in the sera of several, and partly at least, unknown peptides and glycopeptides disclosing opioid activity might be characteristic of schizophrenia.

Rats were exposed to whole body vibration horizontally for four hours at 5 Hz frequency and 2 cm amplitude. Of the components of the plasma kallikrein-kinin system the free (spontaneous) and kaolin-activated kallikrein (prekallikrein) activities, the concentration of bradykinin, the bradykinin splitting total kininase activity, total kallikrein-inhibitor activity and the concentration of alpha 2-macroglobulin, a major plasma kallikrein inhibitor, were estimated. Results showed that in response to acute vibration plasma free kallikrein activity was increased significantly in association with a significant reduction of prekallikrein concentration. The concentrations of bradykinin and total kininase activity were significantly elevated, too. Neither total kallikrein-inhibitor activity nor the concentration of alpha 2-macroglobulin were changed indicating that the plasma kallikrein inhibitors did not play a role in the alterations of plasma free kallikrein and prekallikrein activities. During acute vibration the plasma kallikrein-kinin system was activated probably by the enhanced catecholamine secretion. We suggest that the biological importance of this phenomenon is in the defense against the impaired microcirculation caused by catecholamines.

The regulation of Na+ and water metabolism was studied in sheep with rumen fistula after water deprivation for 48 hours. Na+ and K+ concentrations were determined in blood plasma, blood, urine and saliva, with or without NaCl load. The results showed that the water content of the ruminal fluid plays an important role in the control of electrolyte and water metabolism. The absorption of water and Na+ from the rumen favours the maintenance of isosmolality and isovolaemia until the concentration of Na+ in the ruminal fluid has exceeded that in blood plasma. Thereafter the balance of water movement between rumen and extravascular space is shifted towards the rumen inhibiting thereby a further increase of Na+ concentration and ensuring the life conditions for the ruminal microbial population. During water deprivation not only water is lost but as a result of Na+ excretion relative hyponatraemia also ensues as can readily be assessed from the ratio of salivary Na+ and K+ concentrations. Upon NaCl load the salivary Na+/K+ ratio was increased indicating the extent of Na+ supply.