Effect of D- and/or L-aspartic acids on feeding, drinking, urine outflow and core temperature

Rats were given D- and/or L-aspartic acids (Asp) in saccharin solution for one week. Body weight gain, daily food and fluid intake, weight of faeces, urine outflow and osmolality, and rectal temperature were compared with those of the pretreatment period. After the rats had been sacrificed the weights of liver, spleen and kidney were estimated and compared with those of the control. The long-term oral administration of D-Asp caused a significant decrease in the weights of total body, liver and kidney, in the daily food and fluid intake, in the weight of faeces and in the volume of urine. The osmolality of urine of the rats administered D-Asp was significantly higher than that of the control. The concomitant oral administration of L-Asp seemed to antagonize the effects of D-Asp.

Effect of alpha-adrenergic stimulation on prostacyclin and renin release in the rat kidney

The relationship between renin secretion and PGI2 production, in response to intrarenal infusion of norepinephrine, was examined in the isolated perfused rat kidney. Infusion of norepinephrine in a dose which caused substantial vasoconstriction (100 ng/min), markedly increased urinary excretion of 6-keto PGF1 alpha, the stable derivative of PGI2, without significantly altering renin secretion measured in the effluent perfusate. No change in urinary 6-keto PGF1 alpha occurred when vasoconstriction was prevented by infusing the alpha-adrenoceptor blocking drug phenoxybenzamine (2 x 10(3) ng/min) alongside norepinephrine (100 ng/min). However, under these conditions there was marked stimulation of renin secretion which, as has been demonstrated previously, is mediated by a beta-adrenoceptor. There were significant increases in urine flow rates during both vasoconstrictor and non-vasoconstrictor infusions. These findings clearly indicate that in the rat kidney prostacyclin production and renin release in response to norepinephrine are dissociated.

Denervated and intact kidney responses to norepinephrine infusion in conscious dogs

Effects of moderately hypertensive norepinephrine (NE) infusion on the function of denervated and innervated kidney were determined in conscious dogs chronically prepared by surgical splitting of the urinary bladder performed to enable separate urine collection from each kidney. While blood pressure increased 23 +/- 4 mm Hg and renal hemodynamics tended to increase slightly, sodium excretion of the denervated but not innervated kidney decreased significantly. This indicated a NE-stimulated increase in tubular sodium reabsorption. The effect was limited to the denervated kidney, possibly due to hypersensitivity of this organ's tubules to the circulating catecholamine. Previous blockade of alpha-receptors (phentolamine) appeared to blunt the dissociated response of the two kidneys to NE, whereas beta-receptor blockade (propranolol) did not affect it. This suggests that increasing sodium reabsorption of the denervated kidney depended on stimulation of tubular alpha-receptors. NE infusion impaired urine concentration equally in the intact and denervated kidney.

Potentiation of antidiuretic response to systemic angiotensin II by elevation of CSF NaCl concentration

The antidiuretic effect of the simultaneous intracerebroventricular (ICV) infusion of 0.24 M NaCl (0.02 ml/min) and intravenous (i.v.) infusion of angiotensin II (12 ng/kg X min) was studied in hydrated goats, and was compared to the antidiuretic effects of the separate infusions. The combined infusions inhibited the water diuresis for 30 min, whereas the separate infusions only reduced the water diuresis by 25% (ICV NaCl) and by 50% (i.v. angiotensin). The combined infusions increased the urine osmolality on the average by 415%. Corresponding increases induced by ICV NaCl and by i.v. angiotensin were 100 and 160%. The results suggest that systemic angiotensin II and elevated CSF NaCl concentration interact and potentiate each other as stimuli for antidiuretic hormone secretion. It is postulated that this synergism may help to preserve body water in hypovolemic conditions associated with hyperactivity of the renal renin-angiotensin system.

Aqueous vasopressin response test in clinically normal dogs undergoing water diuresis: technique and results

Studies were undertaken to develop a standard procedure and to establish reference values for an aqueous vasopressin response test in dogs with normal renal function undergoing water diuresis. After IV administration of 5 mU of aqueous antidiuretic hormone (ADH)/0.45 kg of body weight of 13 water-loaded clinically normal dogs, the mean urine specific gravity increased from 1.002 +/- 0.001 to 1.021 +/- 0.0058; the mean urine osmolality increased form 99 +/- 52 mOsm/kg of water to 933 +/- 252 mOsm/kg. The PCV, total plasma protein concentrations, and serum osmolalities decreased in all dogs during water loading and ADH administration, but slowly returned toward base-line values after discontinuing the ADH infusion.

Reposital vasopressin response test in clinically normal dogs undergoing water diuresis: technique and results

Maximal renal concentrating ability after parenteral administration of repositol antidiuretic hormone was evaluated in 13 clinically normal dogs undergoing water diuresis. Urine specific gravity and osmolarity progressively increased in all dogs and generally attained maximum concentrations after 8 to 12 hours. Urine specific gravity values increased from mean of 1.003 +/- 0.001 mOsm/kg of water to a mean maximal value of 1.042 +/- 0.009 mOsm/kg. Urine osmolarity increased from a mean of 132 mOsm/kg to a mean maximal value of 1,518 +/- 242 mOsm/kg. Water intoxication was observed in all dogs due to continued administration of water after antidiuretic hormone administration.

Arginine vasotocin and renal function in the conscious dog

The effects of arginine vasotocin (AVT), 4-6 ng/kg, on renal function and plasma prolactin (PRL) were determined in conscious American foxhounds undergoing a water diuresis. Intravenous AVT produced an antidiuresis, kaliuresis and inconsistent natriuresis, independently of changes in GFR, blood pressure, heart rate and plasma PRL.

Effects of anti-oxytocin serum in Brattleboro rats

Brattleboro rats were housed singly in metabolic cages and continuously infused with saline. Timed urine collections were analyzed for Na+ and K+; oxytocin (OT)-like material was estimated by RIA. OT infusions reduced urine flow and increased Na+ output. Urinary Na+/K+ ratios rose during OT infusion, falling below control values after infusion. Passive immunization with an OT antiserum reduced but did not prevent these renal effects of OT. In a second experiment, immunization had no effect on daily urine volume or Na+ output, even though high titers were achieved and excretion of endogenous OT-like material was reduced. We conclude that endogenous OT has little effect on Na+ excretion in these rats, although pharmacological doses of OT produced their known natriuretic effect.

Effects of saline load, Roentgen contrast medium and indomethacin on diuresis and pelvic pressure in the acute obstructed kidney. An experimental study

In anaesthetised pigs indomethacin (2.5 mg/kg body weight) immediately reduced pelvic pressure above unilaterally and bilaterally totally occluded ureters. Repeated administration of the same dose caused a cumulative reduction of pelvic pressure. In animals with a kidney working against a partial obstruction of the ureter, indomethacin reduced urine production by more than 50% within 15 to 30 min. It was also shown that the effect of indomethacin on the pelvic pressure was dependent on the fluid load of the animals. Rapid infusion of saline or X-ray contrast medium counteracted the pressure fall induced by indomethacin.

Abolition, by dopamine blockade, of the natriuretic response produced by lower-body positive pressure

1. In a preliminary study, a positive pressure of 25 mmHg applied to the lower body raised right atrial pressure by a mean of 7 mmHg. 2. Sustained application of lower-body positive pressure (LBPP) in six normal adult males increased sodium excretion ([Na]V) from a control level of 126.5 +/- 10 mumol/min to 213 +/- 21 mumol/min (P = 0.003) and fractional sodium excretion (EfNa) from 0.7 +/- 0.1 to 1.2 +/- 0.1 (P = 0.001). 3. Urine flow (UF) increased from 0.85 +/- 0.07 ml/min to 4.1 +/- 0.8 ml/min (P = 0.002), osmolar clearance (Cosm) from 2.6 +/- 0.13 ml/min to 4.2 +/- 0.4 ml/min (P = 0.003) and free water clearance (CH2O) from -1.75 +/- 0.1 ml/min to -0.1 +/- 0.01 ml/min (P = 0.001). Creatinine clearance (Ccr) showed no significant change. 4. After dopamine blockade with domperidone, LBPP did not cause a rise in [Na]V or EfNa. However, urine flow, Cosm. and CH2O remained significantly above control values, implying persistent suppression of antidiuretic hormone. 5. Dopamine blockade without positive pressure did not affect basal sodium excretion.

Replacement therapy with arginine vasopressin in homozygous Brattleboro rats

We studied the replacement therapy of different doses of AVP in DI rats. It is surprising that relatively high levels of plasma AVP were needed to achieve significant antidiuretic effects. Measured plasma AVP concentrations are less than those predicted from the release rates of AVP by the minipumps. This difference may be due to the subcutaneous mode of release of AVP. The study also provides evidence that urinary excretion of AVP is a good indicator of the plasma AVP level.

Studies concerning the effects of a pineal peptide extract on collagen metabolism

The effects of Crinofizin (Cfz), cortisone, triiodothyronine (T3) and methylthiouracil (MTU), alone or in association with one another, on collagen metabolism of impuberal and adult rabbits were tested. These effects were assessed by the hydroxyprolinuria (Hyp) assay corroborated with observations regarding mortality, body weight, diuresis and excretion of nitrogenous substances. Cfz given alone stimulated weight gain and did not alter characteristically the Hyp. Cortisone and T3 given in various doses and ways without Cfz induced general phenomena of the antianabolic or catabolic type, affecting characteristically the Hyp, which was low after administration of cortisone and increased after T3; association of Cfz to both cortisone and T3 had general protecting and corrective effects and brought Hyp towards or at normal values. Chronic administration of MTU with or without Cfz did not have significant effects. The corrective value of Cfz by anabolic and anti-catabolic actions on collagen metabolism disturbed by cortisone or T3 in excess is discussed.