[Diuretic activity of the infusion of flowers from Lavandula officinalis]. / Effet diurétique de l'infusion de fleurs de Lavandula officinalis. [Diuretic activity of the flowers infusion of Lavandula officinalis.

The diuretic activity of an infusion of Lavandula officinalis was studied in the Wistar rat. Thus, the kinetics of hydroelectrolytic elimination in response to the oral administration of an infusion of pharmaceutical lavender flowers were measured in the rats. Experiments were completed under similar conditions using a synthetic pharmacological diuretic, Diamox. The aqueous extract of this aromatic plant accelerated the elimination of the water overload. At the peak of the diuretic response, urinary osmolarity was significantly less than that of controls (111+/-14 vs. 195+/-11 mosmol x kg(-1)). Sodium excretion was moderate following administration of the infusion when compared to the synthetic diuretic. The stability of the aldosterone concentrations in the plasma and the absence of correlation with plasma sodium concentrations, coupled with the observed clearance of the free water (0.055+/-0.007 vs. 0.045+/-0.012 mL x min(-1)) show that the increase in diuresis and the moderate increase in sodium excretion are of tubular origin. The result of the phytochemical analysis of hexane extracts in the infusion and in urine indicated that four or five chemical factors may be involved in the diuretic effect of lavender.

[Experimental evidence of an antihypertensive and hypocholesterolemic effect of oil of argan, Argania sideroxylon]. / Mise en évidence expérimentale des effets antihypertenseurs et hypocholestérolémiants de l'huile d'Argan, Argania sideroxylon.

The chronic ingestion of 5 ml/kg/d of Argan oil by spontaneously hypertensive rats restores normal blood pressure and induces hypocholesterolaemia. In order to confirm these results Meriones shawi, a rodent of the Gerbillideae family, was tested as a second animal model. Meriones submitted to a hypercaloric diet and physical inactivity became fat, and exhibited hypertension, dyslipidaemia and hyperinsulinaemia. When treated for two months with the same dosage regimen, decreases in glycaemia, total plasmatic cholesterol, LDL, insulinaemia and systolic and diastolic blood pressures of 4.4 per cent, 14.4 per cent, 32.5 per cent, 26.8 per cent, 28.8 per cent and 30.5 per cent were simultaneously observed. Increases in LDH and of TG of 27.9 per cent and 16.2 per cent respectively were also observed. No effect on body weight occurred. The action of polyunsatured fatty acids of the Argan oil is predominant, but in addition, other constituents play an active part.

[Postnatal development of the kidney concentrating ability, the renin-angiotensin system and the adrenal cortex hormones in the calf]. / Développement post-natal du pouvoir de concentration rénal, du système rénine-angiotensine et des hormones cortico-surrénaliennes chez le veau.

Post-natal development of plasma and urine osmolality, as well as plasma renin activity, aldosterone and cortisol levels were studied in calves between 1 and 9 months of age. The ratio of urine to plasma osmolality rose from 0.8 at an early post-natal age to 3.8 at the end of the study period. Plasma renin activity, plasma aldosterone and cortisol levels did not show any change during the post-natal development period. The plasma concentrations of these hormones were in the same range as is found in the adult.

[Postnatal development of renal concentrating ability in a desert rodent, Jaculus orientalis]. / Développement postnatal du pouvoir de concentration rénal chez un rongeur des zones arides, Jaculus orientalis.

Postnatal development of renal function was studied in newborn Jerboa from six weeks after birth. The results showed that the renal capacity of urine-concentration was more or less analogous to that of the adult, starting 15 weeks after birth when the animal reached a body weight of about 70 to 90 g. From the 13th week onwards, the U/P ratio of the osmolality in function of age, increases when the urinary debit decreases. The osmotic-clearance and the free water-clearance will show stability 15 weeks after birth.

[Effect of vasopressin and indomethacin on provoked diuresis in pregnant and non-pregnant Meriones crassus]. / Effet de la vasopressine et de l'indométhacine sur la diurèse provoquée chez Meriones crassus gravide et non gravide.

The dynamics of induced diuresis was studied in Meriones crassus, a desert rodent species, during estrus and pregnancy. In response to hydration, pregnant Meriones crassus excrete excess water more rapidly than non pregnant females. Diuresis appears earlier in pregnant females indicating a more rapid inactivation of vasopressin. The possible interaction between vasopressin and prostaglandins, and its effect on renal excretion during pregnancy, was studied during arginine-vasopressin treatment and after inhibition of endogenous AVP and prostaglandins. Results show a decrease in renal response to endogenous vasopressin during pregnancy in Meriones crassus, which may be due to the increase in renal prostaglandin levels.

[The effect of glucocorticoids on the diluting capacity of the kidney of a desert rodent: Gerbillus campestris]. / Effet des glucocorticoïdes sur la capacité de dilution du rein chez un rongeur désertique: Gerbillus campestris.

The ability to excrete a water load was studied in Wistar rats and in gerbils (Gerbillus campestris). The rat excreted the entire water load in less than 2 h whereas Gerbillus campestris excreted less than 60% of the water load in 4 h. The gerbils which had received a dose of 15 micrograms/100 g body weight dexamethasone improved their rate of excretion which attained 92 +/- 6% in 2 h 30 min. The antidiuretic hormone (ADH) measured by radioimmunoassay at the time of maximum diuresis was undetectable in rats; in contrast, in gerbils the level of ADH remained relatively high (55.4 +/- 6.7 pg/ml). We conclude that the partial inability of the gerbil's kidney to excrete a water load is due to a high ADH level and probably to a low concentration of glucocorticoids.

[Osmolality and secretion of vasopressins during pregnancy in Meriones crassus]. / Osmolalité et sécrétion de vasopressine au cours de la gestation chez Meriones crassus.

Endocrine and renal parameters were measured in a desert rodent, Meriones crassus. In virgin females, the urine and plasma osmolality was 2018 +/- 136 and 325 +/- 3 mosm/kg (m +/- SEM), the level of circulating vasopressin, 162 +/- 22 pg/ml and the plasma renin activity 14.3 +/- 0.9 ng/ml per h. During pregnancy, the renin-angiotensin system was activated, and the plasma vasopressin values remained similar to those of virgin animals in spite of a lower blood plasma osmotic pressure. During this period, the regulation of the hydromineral balance was modified. These data suggest a lowering of the osmotic thresholds for vasopressin and possibly also for thirst during pregnancy in this desert rodent.

Effect of water intake on Na-K-ATPase in nephron segments of the desert rodent, Jaculus orientalis.

Na-K-ATPase activity was measured in individual pieces of nephron microdissected from collagenase-treated kidneys of jerboas, Jaculus orientalis. Na-K-ATPase activity was high in the distal convoluted tubule, intermediate in the thick ascending limb of the loop of Henle and low in the proximal and collecting tubule. When jerboas were adapted for several weeks to a hydrated diet and excreted a more diluted urine, Na-K-ATPase activity was altered in specific segments of the nephron: 1. In the proximal convoluted tubule, Na-K-ATPase activity decreased, especially in the juxtamedullary nephrons, suggesting that internephron heterogeneity was diminished; 2. In the medullary thick ascending limb, but not in the cortical portion, Na-K-ATPase activity decreased by 30%; 3. Na-K-ATPase was also diminished in the cortical collecting tubules (by 20%) but not in the medullary collecting tubule. Morphometric measurements also indicate that changes in Na-K-ATPase activity observed in the thick ascending limb are correlated to a cell atrophy, whereas in the collecting tubule, they occur independently of any visible morphological alteration. These differences in Na-K-ATPase activity are likely to be secondary to the changes in the plasma concentration of vasopressin previously described during such adaptation and to be involved in the control of water and sodium handling.

Renal excretion capacity in hydrated desert rodents (Jaculus orientalis and Jaculus deserti).

The capacity to excrete a water load was studied in rats and in two desert rodents (Jaculus orientalis and Jaculus deserti) adapted to either 5 or 30 degrees C ambient temperature. The rat is able to eliminate the entire water load regardless of thermal adaptation. Cold-adapted J. orientalis and J. deserti excreted 60% of the water load in comparison to 20-30% in warm-adapted jerboas. At both adaptation temperatures, antidiuretic hormone (ADH) concentration was estimated at maximum diuresis in the two desert species. Though hydration induced a significant decrease in ADH concentration in both species, its level in the plasma remained relatively high. The decrease was more pronounced in J. orientalis than J. deserti.

[Secretion of antidiuretic hormone and renal function during the awakening of Jaculus orientalis from hibernation]. / Sécrétion de l'hormone antidiurétique et fonction rénale au cours du réveil de l'hibernation de Jaculus orientalis.

Chemical analysis of kidney tissue from jerboa (Jaculus orientalis) during hibernation shows that the cortico-papillary gradient of Na+ ions is strongly reduced, whereas that of urea is completely suppressed. During the spontaneous rise in body temperature which occurs as the animal comes out of hibernation, the accumulation of Na+ in the papilla then in the medullary zones begins to increase from 25-30 degrees C body temperature, before the appearance of a urea gradient. This confirms the hypothesis that urea accumulation in the kidney medulla is coupled to active transport of sodium. This active transport may be partially dependent upon circulating ADH, circulating levels of which increase with increasing body temperature. Glomerular filtration in normothermic jaculus orientalis is 696 +/- 155 microliter . min-1 and urinary flow is relatively low in this desert species at 1.12 +/- 0.18 microliter . min-1. During hibernation at a body temperature between 7 and 8 degrees C glomerular filtration and urinary flow are not measurable. Glomerular filtration appears (51 microliter . min-1 at 26 degrees C) and increases at a temperature range where systemic blood pressure has already attained a normal level. This indicates that the reestablishment of glomerular filtration may be linked to intra-renal vasomotor events as is suggested by measurement of plasma renin activity during the coming out of hibernation.

Plasma antidiuretic hormone levels and liver vasopressin receptors in the jerboa, Jaculus orientalis, and rat.

V1 vasopressin, angiotensin, alpha-adrenergic, and glucagon receptors in liver were studied on membrane fractions prepared from two groups of jerboas ( Jaculus orientalis) given dry or water-enriched diets for periods of 4 to 7 weeks, and from rats acutely treated with pharmacological amounts of arginine-vasopressin (AVP) or (1-deamino-8-D-arginine)-vasopressin (dDAVP). Tritiated (8-lysine)-vasopressin ([3H]vasopressin), tritiated (1-asparagine-5-valine)-angiotensin II ([3H]angiotensin II), tritiated dihydroergocryptine ([3H] DHEC ), and iodinated glucagon ([125I]-glucagon) were used as specific labeled ligands of these receptors. The V1 vasopressin, angiotensin, alpha-adrenergic, and glucagon receptors detected in both groups of jerboas were identical to receptors found in rat liver plasma membranes in regard to the apparent dissociation constants for their respective labeled ligands. Furthermore, vasopressin receptors in jerboa liver membranes discriminated as efficiently as rat liver receptors between the natural neurohypophyseal peptides arginine-vasopressin and lysine-vasopressin on the one hand and the structural analogs (1-deamino-8-D-arginine)-vasopressin and (4-valine-8-D-arginine)-vasopressin on the other. The reduction of antidiuretic hormone (ADH) secretion in jerboas fed a water-enriched diet compared to those on a dry diet (75 +/- 25 pM versus 372 +/- 86 pM) was accompanied by an increase in the number of liver vasopressin receptors (2.79 +/- 0.53 versus 1.25 +/- 0.14 pmol [3H]vasopressin bound/mg protein). The modifications observed were specific for vasopressin receptors, as judged by the maximal binding capacities of [3H]angiotensin II, [3H] DHEC , and [125I]-glucagon, which remained unchanged in jerboas whatever the levels of endogenous circulating ADH. Similarly, administration of pharmacological doses of AVP by iv infusion to rats induced, 2 hr later, a loss of about 50% of V1 liver vasopressin receptors, while the numbers and apparent dissociation constants of angiotensin, alpha-adrenergic, and glucagon liver receptors remained unchanged, and V2 kidney vasopressin receptors were almost desensitized. For V1 liver and V2 kidney vasopressin receptors, the desensitization process was strikingly dependent on the antidiuretic/glycogenolytic activity ratio of the peptide used. Thus, im injection to rats of dDAVP (an analog possessing a very high antidiuretic/glycogenolytic activity ratio) induced, 1 hr later, a total loss of V2 kidney receptors without modification of the number and apparent dissociation constant of V1 liver receptors.

Plasma antidiuretic hormone levels and kidney responsiveness to vasopressin in the jerboa, Jaculus orientalis.

The plasma antidiuretic hormone (ADH) concentration and the kidney medulla responsiveness to vasopressin were measured in adult jerboas ( Jaculus orientalis) in different states of hydration. In 15 jerboas adapted to 30 degrees and fed a dry diet, the average ADH concentration in blood plasma was 479 +/- 59 pg/ml, as measured by a radioimmunoassay. About 6 hr after receiving a 5% body wt water load by gavage, the plasma ADH concentration fell to 130 +/- 30 pg/ml in the 5 jerboas still producing hypertonic urine (1022 +/- 267 mosmol/liter) and to 41.5 +/- 8.4 pg/ml in the 6 jerboas producing hypoosmotic urine (157 +/- 6 mosmol/liter). In vitro biochemical experiments were performed on the kidney medullas from two groups of 5 jerboas fed a dry diet (group I) or a water-enriched diet (group II), respectively, for 4 to 7 weeks. Compared to group II, group I animals exhibited (a) higher plasma ADH values, 372 +/- 86 versus 76 +/- 25 pg/ml; (b) higher urine osmolarities (3817 +/- 638 versus 647 +/- 90 mosmol/liter); (c) some decrease in [3H]lysine-vasopressin (LVP) binding capacity to kidney membrane fractions (maximal binding: 0.4 versus 0.6 pmol [3H]LVP bound/mg protein); d) decreased adenylate cyclase responses to arginine-vasopressin, lysine-vasopressin, and oxytocin in kidney membrane fractions; and (e) weaker adenylate cyclase responses to arginine-vasopressin in microdissected pieces of the medullary thick ascending limb of Henle's loop. The values found for (a) the dissociation constant of [3H]lysine-vasopressin binding to membranes (KD); (b) adenylate cyclase sensitivity to the three neurohypophyseal hormones (KA); and (c) adenylate cyclase sensitivity to arginine-vasopressin (KA) in medullary collecting tubules and medullary thick ascending limbs are similar in the two groups of jerboas and roughly comparable to those previously reported for the rat kidney medulla. The reduced maximal adenylate cyclase responses to vasopressin in the jerboas fed a dry diet might indicate some physiological "down regulation" of the number of vasopressin-specific receptors in the kidney as a result of the huge ADH concentration present in blood plasma under these conditions. However, this desensitization is not sufficient to account for the production of hypoosmotic urine in spite of the relatively high ADH plasma levels which persisted after acute overhydration.

[Measurement of antidiuretic hormone and plasma renin activity in desert rodents]. / Mesure de l'hormone antidiurétique et de l'activité rénine plasmatique chez les rongeurs désertiques (Jaculus orientalis et Jaculus deserti).

Plasma antidiuretic hormone (ADH) and renin activity (PRA) were determined in two species of desert rodent (Jaculus orientalis and Jaculus deserti) under chronic dehydration and were compared to those of Wistar Rat. ADH concentration was very high in the desert animals: 200 times higher than in the Rat on a normal diet and 20 times higher than in the 48 hours-dehydrated Rats. The neurohypophyseal ADH content of these rodents was twice that of the normally hydrates Rat, while the dehydration caused a decrease of neurohypophyseal content in the Rat. Plasma renin activity was respectively 2.6 and 3.7 times higher in Jaculus deserti and Jaculus orientalis than in Rats on normal diet, but it was similar to that of dehydrated Rats. During an experimental chronic dehydration, the renin angiotensin system is moderately activated in the desert rodents; but, there is an intensive stimulation of ADH which may play a primordial role in the maintenance of water balance. Now it is necessary to demonstrate how these mechanisms are involved in the natural environment of the animals.