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Biomedical subjects

W Z Traczyk

Publications and source records attributed to W Z Traczyk.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

The lack of influence of some neuropeptides present in the posterior pituitary lobe on the frequency of spontaneous contraction of the isolated heart auricle.

Investigations have shown the presence of a cardiodepressant factor in the fluid incubating the posterior pituitary lobe "in situ", which decreased contraction frequency of the isolated heart auricle (Acta Physiol. Pol., 1984, 35: 460-468). The influence on the spontaneous contraction frequency of the isolated heart auricle of the following synthetic neuropeptides was determined: substance P, leu-enkephalin, met-enkephalin, angiotensin II, arg-vasopressin, oxytocin, delta sleep-inducing peptide and atrial natriuretic factor. It was found that the investigated neuropeptides had no effect on the contraction frequency of the isolated auricle of the heart right atrium of two-day-old rat in a concentration from 2.1 x 10(-7) to 1 x 10(-3) mol/l in the bathing medium and it was concluded that their biological properties differ from the cardiodepressant factor.

Angiotensin II↗
PubMedDate not supplied

Substance P-like peptides and vasopressin release from posterior pituitary lobe incubated in situ after intracarotid injections of hypertonic solution in rats.

The experiments were performed on male rats, drinking 2% NaCl solution ad libitum for 12 days instead of tap water. The pituitary gland was exposed by the transpharyngeal approach under urethane-chloralose anaesthesia. The posterior lobe remained in neural and partial vascular connection with the hypothalamus, whereas the anterior lobe was entirely removed. Samples of the outflow medium from the incubated in situ rat posterior pituitary lobe were collected during 30 min intervals. Substance P-like peptides and vasopressin activities were assayed by the biological tests. Injections of hypertonic solution into the internal carotid artery did not change vasopressin release, but induced an increase in Substance P release from the posterior pituitary lobe into the incubation medium. Under conditions of unexcitability of the osmosensitive cells, triggering vasopressin release, the injection of hypertonic solution into the internal carotid artery stimulated the Substance P-like peptides release from the posterior pituitary lobe.

Animals↗
PubMedDate not supplied

Substance P in the blood plasma in hypophysial portal vessels.

The aim of the present study was to check if Substance P (SP) is released from the hypothalamus into the hypophysial portal vessels and by this route exerts its direct influence on the adenohypophysis. For this purpose SP radioimmunoactivity was assayed in the blood plasma collected from hypophysial portal vessels and from the cephalic end of the external jugular vein. The SP levels in blood plasma collected from hypophysial portal vessels and from the jugular vein do not differ significantly. Neither does application of a noxious factor, such as bilateral femoral bone fracture, change significantly the SP level in the blood plasma from portal vessels and from the jugular vein. Hypoxia seems to increase the SP level in portal blood plasma and may be followed by its decrease. It is concluded that hypothalamic SP is not released into the hypophysial portal vessels under normal conditions and its direct influence on the adenohypophysis is not mediated this way.

Animals↗
PubMedDate not supplied

Appearance of a cardiodepressant factor in the medium incubating in situ the posterior pituitary lobe of the rat. II. Differentiation from other active compounds.

In the previous article the occurrence of cardiodepressant activity in the fluid incubating in situ the posterior pituitary lobe of the rat was described (Acta Physiol. Pol., 1984, 35, 460-468). In the present study the cardiodepressant fraction of the medium incubating in situ the posterior pituitary lobe was subjected to further purification by means of thin-layer chromatography on Silica gel G. Three fractions were isolated, one of which caused a 69% decrease of beating rate of an isolated auricles of the right atrium in the two-day-old rats. In this fraction the presence of neither lipids nor compounds containing phosphate residue was detected. On the basis of the site of elution of the cardiodepressant fraction from the column filled with Sephadex G-15, it was demonstrated that the molecular weight of the cardiodepressant factor was less than 1500 and more than 832. The obtained results show that the cardiodepressant activity is associated with a low-molecule compound, probably with peptide structure, which is released into the fluid incubating in situ the posterior pituitary lobe.

Animals↗
PubMedDate not supplied

Mechanism of the post-haemorrhagic vasopressin release from the posterior pituitary lobe.

The mechanism of post-haemorrhagic vasopressin release from the neurohypophysis was studied in rats anaesthetized with urethane. Neurohypophysial vasopressin content was determined according to Dekański and plasma renin activity by radioimmunoassay. In animals bled (1.5% body weight) 60 min after induction of anaesthesia and 30 min after bilateral nephrectomy vasopressin content of the posterior pituitary was significantly higher than in sham-nephrectomized rats. However, when haemorrhage was produced 240 min after induction of anaesthesia and 210 min after nephrectomy, the neurohypophysial vasopressin content was low and similar as that in non-nephrectomized animals. It is concluded that in the phase directly following haemorrhage vasopressin release depends on acute activation of the renin-angiotensin system. Other mechanisms, possibly circulatory reflexes, are involved in the late phase, during prolonged anaesthesia.

Anesthesia↗
PubMedDate not supplied

Release of oxytocin and substance P-like peptides from the rat posterior pituitary lobe incubated in situ after infusion of hypertonic solution into the third cerebral ventricle.

Release of oxytocin and Substance P-like peptides from the rat posterior pituitary lobe incubated in situ after infusion of hypertonic solution into the third cerebral ventricle. Acta Physiol. Pol., 1978, 29 (1): 9-16. The experiments were carried out on male rats. Under general urethane and chloralose anaesthesia the ventral surface of the hypothalamus and the pituitary gland were exposed by a transpharyngeal approach and the anterior pituitary lobe was entirely removed. The posterior lobe with the remaining neural and partially vascular connections with the hypothalamus was incubated in situ. Oxytocin and Substance P-like peptides were assayed biologically in six 20-min samples of the fluid outflow from the posterior pituitary lobe incubated in situ. At the beginning of collection of the fourth sample a hypertonic solution was infused into the third ventricle through a micropipette. This infusion increased significantly the release of oxytocin and insignificantly that of Substance P-like pepides from the posterior pituitary lobe into the incubation fluid.

Animals↗