Acta physiologica Polonica最新文献

The effect of collagen degradation products (CDP I--molecular weight circa 3000 D and CDP II--molecular weight circa 1200 D) on the central dopaminergic system was studied. Differences in the action of both these fractions in the apomorphine stereotypy test were noted; CDP I administered to rats in a dose of 5 micrograms just before application of the drug inducing the stereotypy enhanced the stereotypic behaviour of the animals whereas a dose of 40 micrograms significantly inhibited such behaviour. CDP II, on the other hand, had no effect on this type of stereotypy. Both fractions given in doses of 15 and 40 micrograms enhanced the stereotypy induced by amphetamine. CDP I and CDP II (15 and 40 micrograms) administered 30 min before observation of the animals intensified the cataleptic action of haloperidol, whereas both fractions (CDP I and CDP II) when administered 45 min before observation reduced the catalepsy.

The effect of disodium cromoglycate on skin wound healing and collagen formation in the wounds was studied. Disodium cromoglycate (a mast cell stabilizer) administered to the rats in a dose of 2 mg/animal was found to retard wound healing and markedly increased wound surface in all examined days (3rd, 5th, 7th, 10th, 14th day of healing). The mast cell stabilizer injected directly into wounds decreased collagen content, especially on 10th and 14th day of the healing process.

The central effects of pancreatic glucagon and insulin given intracerebroventriculary (i.c.v.) upon sympathetic activity in the cervical trunk and adrenal nerve were examined in Wistar Kyoto rats. Glucagon i.c.v. administration led to an increase in sympathetic nerve activity in both nerves. Insulin injected into lateral ventricle caused opposite to glucagon inhibitory influence on sympathetic discharge in the cervical trunk and adrenal nerve. This two different central effects of glucagon and insulin on sympatho-adrenal system may contribute to glycemia homesthasis.

Blood pressure, heart rate, aortic nerve activity and cervical sympathetic discharge were recorded simultaneously in 10 rabbits. Chronic recordings were made with electrodes implanted to the uncut aortic and cervical sympathetic nerves. 1. The alerting acoustic stimulus produced a short lasting decrease in sympathetic activity with a transient bradycardia. 2. In 6 out of 8 rabbits i.v. administration of naloxone chloride (100 mg/kg) diminished or abolished early inhibitory effects evoked by acoustic stimulus. 3. The sympatho-inhibitory system involved in the startling response appears to be independent of the baroreceptor inhibitory reflex and has opposite responsiveness to naloxone. 4. A decrease in efferent sympathetic activity with no accompanying change in the aortic nerve activity suggests some central resetting of the baroreceptor-sympatho-inhibitory reflex. 5. We suggest that the observed autonomic effects following an alerting stimulus are typical for a fear-anxiety drive.

Thermal responses to prazosin (0.75 mg/kg, i.v. as a bolus injection or 3 h infusion) were investigated in febrile rabbits (treated with E. coli lipopolysaccharide, PLPS) at 3 ambient temperatures (Ta) of 5, 19, 28 degrees C. The drug produced antipyresis which increased with the simultaneous drop of Ta. This antipyretic activity was accompanied by an inhibition of heat production or enhanced elimination of heat, depending on Ta. It is suggested that antipyresis produced by prazosin is mainly due to the effector part of the thermoregulatory system.

The inhibitory action of caffeine on calcium (Ca2+) release from the sarcoplasmic reticulum (SR) and interference with mitochondrial (Ca2+) fluxes by a mitochondrial uncoupler protonfore CCCP were utilized to define a calcium pool responsible for potentiation of post-rest twitch tension in guinea-pig atria. The Ca2+ fluxes were assessed by means of 45Ca2+. Caffeine and CCCP when applied separately did not affect post-rat 45Ca2+ content. Yet, when they were applied together it was markedly reduced to the resting level. It is concluded that a possible source of contractile Ca2+ may be located in mitochondria and an eventual shift of Ca2+ between mitochondria and the SR seems to be a plausible assumption.

Earlier studies from this department have demonstrated that neurones of the V-th nerve motor nucleus (NVmt) have oligosynaptic, inhibitory output to the inspiratory motoneurone pool being themselves under the influence of a polisynaptic input from vagal afferents. To check the hypothesis that NVmt is a part of the pneumotaxic mechanism, we studied the effects of pharmacological mictroblockade of the NVmt on Breuer-Hering reflexes in halothane-anaesthetized, paralyzed and artificially ventilated rabbits. Activities of NVmt neurones and phrenic nerve firing were recorded. Acid-base balance was controlled and histologic examinations were routinely performed. Expiratory activities were regularly found in NVmt. Its blockade elicited a typical apneustic breathing. During the blockade the Breuer-Hering reflexes gave "paradoxical" effects: an increase in central respiratory frequency following inflation, inspiratory apneusis in response to deflation. We conclude that the NVmt is an important component of the pneumotaxic mechanism or even the anatomical substrate of the pneumotaxic "centre".