Acta physiologica latino americana最新文献

The isolated liver of rats treated with dexamethasone, hydrocortisone, and deoxycorticosterone acetate (DOCA) was perfused with Krebs-Ringer Bicarbonate (KRB). The liver of adrenalectomized rats was also perfused with KRB. The glomerulopressin activity of the ultrafiltrate of the liver perfusates was assayed in the tonic tension contraction (TTC) of isolated stomach fundus from rats. As glomerulopressin is known to be a glucuronide, it was inactivated with beta-glucuronidase to confirm that the effect on the stomach fundus was due to the glomerulopressin and not to an autacoid. It was observed that dexamethasone, hydrocortisone and DOCA inhibit glomerulopressin production, but adrenalectomy had no effect, therefore it can be deduced that the adrenals are not necessary for the production of glomerulopressin.

Acute experiments documented the peripheric action of tricyclic antidepressives (imipramine, chlorimipramine and amitriptyline). They evoked a significant hypotensive action (P less than 0.02), baroreceptor blockade and higher intensity and duration of pressor responses to exogenous noradrenaline, electric stimulation of the sympathetic nerves of the spleen, posterior hypothalamus or the central extremity of vagus nerve. These effects could be produced by the inhibition of noradrenaline reuptake and are antagonized by noradrenergic blockade with phentolamine. Nomifensine does not change arterial pressure, but its analeptic effect is able to awake anesthetized dogs. The pressor noradrenergic response is greater than that obtained with tricyclic antidepressives. The potentiation showed by the injection of dopamine was similar to that produced by imipramine. Injected into the cerebral ventricles of the dog, it did not changed arterial pressure, but crossed the blood-brain barrier. High doses of tricyclic antidepressives and nomifensine evoked inhibitory effects on adrenergic responses.

Administration of vitamin D3 or 1,25 (OH)2D3 to rachitic chicks produces a decrease of 45Ca uptake by mitochondria from intestinal mucosa. This effect of vitamin D3 shows tissue specificity, since it was not observed in liver mitochondria from the same animals. The Km values were similar (about 10 microM) for intestinal mitochondria from rachitic and treated animals. The Ca2+ efflux in previously loaded mitochondria was not changed by treatment. The Ca content of recently isolated mitochondria was strikingly lower after vitamin D3 administration. It is concluded that vitamin D3 may participate in the mechanism which regulates the intramitochondrial Ca concentration.

The sensitivity of cardiac enzymes (GOT, a-HBDH, LDH, LDH-1, CPK and CPK-MB) was studied in the isolated rat heart subjected to 0 (non-ischemic), 20, 30 and 40 min of total global ischemia (0 ml/min) followed by reperfusion in which three consecutive perfusate samples were collected for enzymatic measurements. Cardiac function, estimated by peak tension (Tp), maximal rate of tension development (Tc) and relaxation (Tr) decreased to 0 with ischemia and recovered with reperfusion to 100% in the 20 min, 50% in the 30 min and 10% in the 40 min ischemic groups. In these three groups, enzymatic release, measured as the relative increment (RI) with respect to the control samples, gave significantly higher values than those of non-ischemic hearts (P less than 0.001). LDH-1 was the most sensitive enzyme (P less than 0.0005) for the detection of ischemia in these experimental conditions.

The antistress and antifatigue properties of a Chinese ginseng preparation were tested on Swiss albino mice, exposed to various experimental models of stress, and were compared with those of piracetam. Both ginseng and piracetam were administered chronically in drinking water for 16-18 days as well as acutely, by injection, 30-60 min prior to the experiments. Reactivity of the mice, loss in body weight, amount of faeces, length of endurance and incidence of mortality were graded and measured. Both piracetam and ginseng treatment provided good protection against electroshock stress when compared to the untreated mice; fighting scores, incidence of tonic convulsion and mortality were significantly less in the treated groups. In the heat stress experiments, both piracetam and ginseng provided significant protection to the treated mice against exposure to heat. In the fatigue stress of forced swim test, ginseng treatment provided effective adaptation to fatigue and increased endurance in both male and female mice; piracetam showed some antifatigue effects on the male mice only. In the locomotor activity tests, ginseng did not depress motility, while piracetam did so in the later part of the tests. These results are discussed in the light of the antistress properties of the drugs as reported in the literature.

Diagnosis of guinea pig pregnancy by the inhibition hemagglutination test used to detect chorionic gonadotrophin in urine showed to be unreliable after the 57% false positive and 3% false negative results obtained over 79 urine samples tested. On the other hand, by comparing the cell morphology of about 60 vaginal smears taken from 20 non-pregnant guinea pigs, stained by a Papanicolaou modified technique, the 4 estrous cycle stages were characterized. The subsequent study of many vaginal smears taken from 15 pregnant guinea pigs showed no pathognomic cells but a picture where 60-70% proestrus and 40-30% diestrus cells appeared. This proestrus-diestrus (Pd) picture was accepted as typical for pregnancy, because it showed up in every pregnant guinea pig lasting all the gestation period, changing only after delivery or abortion. Fecundation does not change the estrous cycle sequence which, as it was proved, progressed normally until it reached this Pd picture. Therefore, the persistence of a Pd picture during +/- 6 days should be considered as diagnosis for pregnancy; when estrus has been detected a Pd picture 12-14 days post estrus as prognosis, and at 16-19 days post-estrus as diagnosis for pregnancy. This cytologic assay proved to be reliable. Besides, once cell characterization has been performed, the staining procedure can be substituted by a direct observation of wet specimen, saving time without loosing accuracy.

Behavioral effects of monocularity were assessed in rats, by means of visual discrimination training in a jumping box. The results showed that the experimental subjects did not differ from controls in brightness discrimination, however, were significantly inferior on a conditional discrimination task. This particular test involves the association of present cues with previously learned ones. Since previous work proposes the consideration of the rat's brain as a functional split-brain, and in our condition the visual information was highly lateralized only to the contralateral hemisphere, we suggest that our results may be due to an impairment produced by the reduction of the brain mass available for the discrimination.