Search PubMed⌕ Search

Biomedical subjects

J Zicha

Publications and source records attributed to J Zicha.

142 records · Page 8Linked to original sources
PubMed1981

Hypertension in Brattleboro rats and the injurious influence of salt in youth.

The effect of long-term intake of 0.6% NaCl solution on survival of Brattleboro rats, both homozygous for diabetes insipidus (DI) and heterozygous (non-DI), was investigated. Studies included whether the survival of animals could be influenced a) by the age at which the high salt intake started (either from prepuberty, i.e. from the 4th week, or after sexual maturation, i.e. from the 12th week of age); b) by uninephrectomy (UNX) which elicited hypertension in DI rats drinking saline from youth. All non-DI and those DI rats that drank saline only from adulthood, survived for the whole duration of the experimental, i.e. 14 weeks. Only 43% of animals survived in the group of DI rats drinking saline from youth. This high mortality was reduced by UNX carried out either simultaneously or 8 weeks after the onset of saline drinking. DI rats consumed several times more saline than non-DI rats. Nevertheless, the consumption was greater in the low-mortality than in the high-mortality group. Salt intake was moderately lowered by UNX. Plasma Na+ concentration was higher in rats of the high-mortality group and it was not affected by UNX. In DI rats plasma volume was greater than in non-DI rats and its values in the low-mortality group exceeded those ones of the high-mortality group. It was decreased by UNX in the low-mortality group but this was not true for the high-mortality group. It is concluded that high mortality in DI rats consuming saline from prepuberty is abolished by the intervention producing hypertension. The role of hypertension in a protection against the toxic effects of salt is discussed.

Age Factors↗
PubMed1979

Effect of age on hypertensive stimuli and the development of hypertension in Brattleboro rats.

1. In rats with inherited diabetes insipidus, unilateral nephrectomy plus drinking of 0.6% NaCl solution (saline) did not influence blood pressure in adult rats. However, when these factors applied before puberty, they produced hypertension. 2. We therefore analysed whether saline administration before puberty or unilateral nephrectomy before puberty was more important for this hypertensive response. 3. Saline drinking was found to be necessary for the response because hypertension was elicited by unilateral nephrectomy in adult rats only if saline consumption began before puberty.

Aging↗
PubMed1977

Hypertension in rats with hereditary diabetes insipidus. The role of age.

The effect of age, sex and salt intake on the hypertension produced in homozygous (DI) and heterozygous (non-DI) Brattleboro rats and Long Evans rats was studied. The left kidney was removed at the age of 25, 35, 50 and 80 days (UNX 25, UNX 35, UNX 50, UNX 80), and 0.6% NaCl solution or water was offered as drinking fluid. In UNX DI rats drinking saline the mean value of blood pressure (BP) exceeded 150 torr. The highest values of BP were observed in DI UNX 25 females while no hypertension occurred in rats UNX 80. There was no correlation between individual values of BP and saline consumption in DI females with hypertension. However, individual BP values correlated with the urinary Na+/K+ ratio measured in the course of 24 h of water deprivation, due to age-dependent sodium excretion the values of which were highest in the UNX 25 group. Hydronephrosis was present in all DI rats with manifest hypertension. In hypertensive animals, BP values, Na+/K+ ratio and the frequency of hydronephrosis exhibited the same age dependence. The role of age and adaptability to the increased saline intake in the susceptibility of DI rats to experimental hypertension is discussed.

Age Factors↗
PubMed1977

Blood pressure and water and electrolyte intake and excretion in rats (Brattleboro strain) after unilateral nephrectomy.

Using Brattleboro rats with and without hereditary diabetes insipidus (DI, non-DI), blood pressure, water intake and the excretion of water, sodium, potassium and osmotically active substances were measured in intact individuals and in animals subjected to unilateral nephrectomy at the age of 23 or 80 days. The development of blood pressure (BP) changes, determined in unilaterally nephrectomized animals at the age of 4--6 months, depended on the age at which the kidney was removed. After nephrectomy at the age of 25 days, hypertension developed only in DI females given 0.6% NaCl solution to drink. The BP of those which drank water was unaffected. Unilateral nephrectomy at the age of 80 days produced a slight BP increase in females irrespective of whether they drank water or 0.6% NaCl, but in males only if they drank 0.6% NaCl solution. No hypertension was observed in intact animals. No relationship was found between water intake and the blood pressure level. The BP increase in water-drinking females uninephrectomized at 80 days was accompanied by a raised urine flow and raised excretion of osmotically active substances. Sodium losses in DI animals were greater than in non-DI animals and the urinary sodium concentration, in maximum dehydration, attained minimum values in DI and maximum values in non-DI animals. Unilateral nephrectomy at 25 days increased sodium losses in all the animals except non-DI females, but when performed at 80 days, only in DI males. No relationship between these results and BP changes was found. The possible relationship of the extrarenal consequences of absence of vasopressin to the development of experimental hypertension are discussed.

Animals↗
PubMed1976

Single nephron glomerular filtration rate ratios of superficial, intercortical and juxtamedullary nephrons in rats during development.

In 20, 40 and 60-day-old rats the filtration rate was studied using Baines modification of Hanssen's Na4Fe (14CN)6 method enabeling the determination of single nephron glomerular filtration rate (SNGFR) ratio between superficial (S), intercortical (I) and juxtamedullary (J) nephrons. The proximal tubule lengths were determined as well. A close correlation was obtained between age and S/I, I/J and S/J of proximal tubule lengths and between age and I/J, S/J 14C-activities of ferro-cyanide. Presented findings confirm the data on the increasing role of superficial nephrons in the course of postnatal development of rat.

Age Factors↗
PubMed1975

The pineal gland and the effect of neonatal administration of androgen upon the development of spontaneous salt and water intake in female rats.

The effect of pinealectomy (PX) and sham-pinealectomy (SPX) on the calculated concentration of NaCl in the total volume of fluid drunk per day ([NaCl]I) in female rats offered a free choice between water and 3% NaCl solution was measured. In normal rats the [NaCl]I increases after attainment of sexual maturity. The increase can be accelerated by neonatal PX. Neonatal 'masculinization' of female rats by testosterone propionate (TP2) removes the increase of [NaCl]I in adult females and suppresses the acceleration due to PX. Neonatal SPX interferes with this decreasing effect of TP2 in adult female rats. The role of the pineal gland in the regulation of water and salt intake is discussed in relation to sex differences, sexual maturation and neonatal stress.

Animals↗