PubMed Health⌕ Search

Biomedical subjects

B Lichardus

Publications and source records attributed to B Lichardus.

At least 73 records · Page 4Linked to original sources
PubMed1984

Acute stress stimulates the red cell sodium pump in rat.

The effect of restraint stress (RS) on the red cell sodium pump, hematocrit, plasma osmolality and plasma sodium and potassium concentrations was measured. Ten min of RS did not produce any change in the sodium pump activity. Longer lasting stress - 150 min - stimulated significantly the sodium pump activity in comparison to the control group (8.52 +/- 0.76 vs. 7.78 +/- 0.46 min-1 per 10(13) Ery; P less than 0.05; means +/- S.D.). Hematocrit rose during the stress (controls: 44.8 +/- 2.3; 10 min RS: 48.1 +/- 1.1; 150 RS: 47.0 +/- 1.9%; P less than 0.01 and P less than 0.05, respectively). The values for osmolality and plasma sodium concentration did not change. However, the plasma potassium concentration decreased significantly after 150 min of RS (4.63 +/- +/- 0.74 vs. 3.3 +/- 0.48 mmol 1(-1); P less than 0.001). Thus, acute stress stimulates the sodium pump activity in erythrocytes of the rat and norepinephrine seems most likely to trigger this activation.

Animals↗
PubMed1984

Hypertension induced by repeated stress: possible participation of sympathetic-adrenomedullary catecholamines.

Several groups of male Wistar rats weighing 250-300 g were subjected to immobilization stress (IMO) for various intervals (2.5 h to 19 h daily omitting weekends for a total of 2 to 15 weeks). Blood pressure (BP) was measured with the aid of indirect cuff pressure method under routine conditions once weekly during the whole period of immobilization and in some groups also for 10 weeks after the end of this period. It was found that BP significantly increased after 2 weeks of 2.5 h IMO daily and progressively increased later on. There was an indirect relationship between the duration on individual intervals of IMO and the period which was necessary to develop a significant increase of BP. Adrenal medullectomized animals showed a significantly less increase of BP than normal ones during 16 weeks course of IMO. The level of adrenaline and noradrenaline was significantly increased in animals having 24-hour rest after 39th IMO compared to controls, the blood being taken by chronically implanted cannula in a tail artery.

Adrenal Medulla↗
PubMed1983

The impairment of osmoregulation in the rat offsprings of hyperadiuretic mothers is probably of renal nature.

Experimental hyperadiuretism in pregnant rats was induced by applying them daily throughout the pregnancy a synthetic analogue of vasopressin--dDAVP (1-deamino-8-D-arginine vasopressin). It brought about a moderate alteration in the ability to produce hypertonic urine in their offsprings. The osmoregulatory function in the offsprings in the course of fetal development could have been suppressed either by a direct or an indirect effect of dDAVP i.e. by the hypotonicity of mothers' internal environment. There is by now some evidence based on the simultaneous determination of urinary vasopressin and osmolality that the impairment of the osmoregulatory function may be, at least partly, on the renal level.

Animals↗
PubMed1980

Decreased free water excretion after indomethacin in the absence of antidiuretic hormone in saline loaded hypophysectomized Wistar and hydrapaenic Brattleboro rats.

Indomethacin (40 mg kg-1 in a single dose) was applied by stomach tube to inhibit the synthesis of prostaglandins during extracellular fluid volume expansion with isotonic saline in normal and acutely (2 h) hypophysectomized Wistar rats and hydropaenic diabetes insipidus Brattleboro rats. In the normal rats indomethacin reduced urine output due to decreased free water excretion. In the rats deprived of antidiuretic hormone (ADH) by acute hypophysectomy or due to hereditary eror in ADH synthesis indomethacin also decreased the urine output and clearance of osmotically free water. It is concluded that also other mechanisms besides the established competition between ADH and prostaglandins for ADH receptors may be responsible for the indomethacin effect on the osmotic movement of water in the distal nephron.

Animals↗