Administration Of Ethacrynic Acid Research Articles

Renal gluconeogenic response to different diuretics. II. Glucose production in the early hours after mersalyl, furosemide and ethacrynic acid administration

The effect of mersalyl, furosemide and ethacrynic acid administration on renal glucose production was investigated in rat renal tubules. Administration of ethacrynic acid at a dose of 50 mg/Kg animal weight provoked a transient inhibition of gluconeogenesis which became significant 3 1 2 hours after injection. Administration of an identical dose of furosemide did not affect glucose production whereas mersalyl at a dose of 15 mg/Kg exerted a severe impairment as early as 30 minutes after injection, which lasted for a long period of time. The in vivo effects of diuretics on gluconeogenesis correlate well with the previously observed in vitro effect, although ethacrynic acid showed less potency as an inhibitor in the former, probably because of its rapid clearance.

Cochlear Vessel Permeability to Horseradish Peroxidase after Diuretic Administration in the Chinchilla

The permeability of strial vessels to the small protein, HRP, was examined after administration of diuretics to determine if increased vascular permeability is a factor in the development of strial edema as it is in acoustic trauma. Chinchillas were injected with HRP and either ethacrynic acid, a loop-inhibiting diuretic, or mannitol, an osmotic diuretic. There was no increased vascular permeability to HRP. Therefore, unlike the increased vessel permeability of HRP seen after an acoustic insult, increased vessel permeability of HRP is not a factor in the formation of strial edema after either mannitol or ethacrynic acid administration.

Effects of ureteral occlusion and ethacrynic acid infusion on renal prostaglandin degradation in the dog

The two major renal prostaglandins PGE2 and PGI2 are partly metabolized during a single passage of the kidney. To examine whether stopping glomerular filtration affected the renal degradation, PGE2 and PGI2 were infused into the suprarenal aorta of dogs during ureteral occlusion. Prostaglandin synthesis was blocked by indomethacin, 10 mg kg-1 b.w. i.v. About 20% of PGI2 and 80-90% of PGE2 were metabolized during one passage through the kidney. Prostaglandin degradation and arterial input were proportional (r greater than 0.95). Compared to control conditions at free urine flow, PGI2 degradation was not changed, whereas the degradation of PGE2 was slightly increased by ureteral occlusion. Ethacrynic acid might reduce degradation of PGE2 by inhibiting two degradation enzymes. To examine the influence of ethacrynic acid, PGE2 was infused in different doses into the suprarenal aorta of dogs before and after administration of ethacrynic acid 3 mg kg-1 b.w. i.v. At all dose levels of PGE2, 75-80% was degraded by one passage through the kidney, whether ethacrynic acid was administered or not. However, although ethacrynic acid did not alter the total renal output, the urinary fraction was reduced from 20-30% to 10-15%. We conclude that degradation of both PGE2 and PGI2 is mainly confined to the blood vessels, and that ethacrynic acid in conventional doses does not prevent degradation of PGE2, but redistributes PGE2 output from urine to renal venous blood.

Simultaneous investigations of elemental changes in individual cells of the stria vascularis and in endolymph.

Using the microprobe for energy dispersive X-ray microanalysis, the elemental compositions of both the individual cells of the stria vascularis and of the endolymph were followed simultaneously under normal conditions and after the administration of 120 mg/kg ethacrynic acid (EA). Marginal cells and intermediate cells showed reversible increases in potassium and decreases in sodium concentrations. Shifts in the ionic composition of endolymph occurred later than after elemental changes in the strial cells. The present results indicate that the marginal and the intermediate cells are the primary target for EA-induced ototoxicity. However, generalized toxic effects of EA are also indicated, with a general leakage of different elements occurring during the 30-60 min period after EA administration.

Control of atrial natriuretic factor release in conscious dogs.

The aim of this study was to examine the changes in the concentration of plasma immunoreactive atrial natriuretic factor (iANF) that occur in response to expansion or depletion of the extracellular fluid volume in conscious dogs. The plasma iANF concentration was also measured postprandially after the ingestion of a meal containing 125 meq of sodium. Postprandial plasma iANF increased 45% (P less than 0.05) above the base-line concentration, and this increase was accompanied by a brisk natriuresis. After a low-sodium meal, however, plasma iANF and sodium excretion failed to increase. The plasma iANF concentration increased from 57 +/- 5 to 139 +/- 36 pg/ml (P less than 0.05) immediately after volume expansion with intravenous isotonic saline infusion (2.5% body wt) administered over a 30-min period; plasma iANF remained elevated at 90 +/- 14 pg/ml (P less than 0.05) for an additional 30 min before returning toward preinfusion levels. Plasma iANF decreased 45% from 78 +/- 17 to 43 +/- 7 pg/ml (P less than 0.05) in response to the administration of ethacrynic acid (2.0 mg/kg, iv bolus) that produced an estimated 15% depletion of intravascular volume. In additional experiments the infusion of synthetic alpha-human ANF at 100 and 300 ng X kg-1 X min-1 increased (P less than 0.05) both the plasma iANF concentration and the urinary excretion of iANF. This study demonstrates that the secretion of ANF is consistently influenced by changes in the extracellular fluid volume. Furthermore, the results support the concept that ANF functions to increase postprandial sodium excretion following the ingestion of a high-sodium meal.

Ultrasonic electrocochleography in guinea pig.

In order to obtain information about how ultrasonic stimuli are perceived (USP) in man, guinea pig cochleae were stimulated by bone conduction with frequencies (98.8 and 143.5 kHz) above the normal auditory field of this animal. The cochlear potentials recorded consisted of CM, SP and AP originating from the basal turn of the cochlea, and were found to be influenced by asphyxia, administration of ethacrynic acid, hypothermia and change of interstimulus interval. In addition, in kanamycin-treated animals the mean AP amplitude decreased to about one fourth of the normal value, and the mean AP latency increased significantly. These findings suggest that there is no special sense organ for the detection of USP but that such sounds activate hair cells in the basal turn of the cochlea.

Effects of ethacrynic acid in the newborn infant

The effects of ethacrynic acid on electrolyte and water excretion were examined in 10 neonates with fluid overload states. Ethacrynic acid (1 mg/kg IV) produced a 10-fold increase in FENa+ and FECl - and a sixfold increase in urine volume and osmolar clearance. These effects peaked within 1 hour of ethacrynic acid administration, and progressively decreased to the baseline value by 5 hours after drug administration. The mean excretion of potassium increased by 280% in 1 hour, and returned to baseline value after 5 hours. The mean Ca++ excretion increased fourfold after 1 hour, and the effect lasted for 4 hours. Two infants developed mild hyponatremia. Our data emphasize the prolonged diuretic and saluretic effect of ethacrynic acid in neonates.

Gap junctions in the stria vascularis and effects of ethacrynic acid.

Gap junctions in the stria vascularis of guinea pigs were studied using freeze-fracture. Nearly all junctions were associated with basal cells. They were present between basal cells and spiral ligament cells, adjacent basal cells, basal and marginal cells and basal and intermediate cells. Following administration of ethacrynic acid, gap junction morphology altered. There was a statistically significant decrease in the centre-to-centre spacing of gap junction subunits and the subunits became regularly packed. Such changes were distinct before any other gross morphological change in the stria had occurred. These morphological alterations suggest that physiological uncoupling of stria cells may occur in response to the effects of ethacrynic acid.

Glomerulotubular balance and prostaglandin synthesis.

We have tested a hypothesis proposed to explain glomerulotubular balance (GTB) as a consequence of variations in prostaglandin synthesis. Arachidonic acid (40 micrograms x kg-1 x min-1) infused into the renal artery of anesthetized dogs raised renal blood flow (RBF) by 41 +/- 5% in hydropenic and by 24 +/- 11% in volume-expanded dogs, but the absolute changes were similar. The infusion of arachidonic acid after the administration of indomethacin (10 mg x kg-1) had no effect on RBF. Arachidonic acid infusion increased the excretion of sodium and chloride in hydropenic dogs but not after the administration of ethacrynic acid in volume-expanded dogs. During continued infusion of ethacrynic acid, the glomerular filtration rate (GFR) was lowered by suprarenal aortic constriction and raised by carotid constriction. A linear relationship between electrolyte reabsorption and GFR (GTB) was observed when GFR was varied between 20 and 110% of control. GTB and tubular reabsorption at comparable GFR were not significantly altered during arachidonic acid infusion or after indomethacin administration. In all experimental settings, bicarbonate, chloride, and sodium reabsorption were altered in molar ratios of 1:2:3 during variations in GFR. We conclude that GTB is independent of variations in prostaglandin synthesis.

超音波刺激によるか電図

In order to obtain information about how ultrasonic stimuli are perceived (USP) in man, guinea pig cochleae were stimulated by bone conduction with frequencies (98.8 and 143.5 kHz) above the normal auditory field of this animal. The cochlear potentials recorded consisted of CM, SP and AP originating from the basal turn of the cochlea, and were found to be influenced by asphyxia, administration of ethacrynic acid, hypothermia and change of interstimulus interval. In addition, in kanamycin-treated animals the mean AP amplitude decreased to about one fourth of the normal value, and the mean AP latency increased significantly. These findings suggest that there is no special sense organ for the detection of USP but that such sounds activate hair cells in the basal turn of the cochlea.

Evidence for bicarbonate-dependent magnesium reabsorption.

During ethacrynic acid administration about 50% of the filtered load of magnesium is reabsorbed. To examine whether the remaining component of magnesium reabsorption is bicarbonate-dependent, i.e. varies with factors known to alter passive reabsorption, experiments were performed in anesthetized dogs. During ethacrynic acid administration MgCl2 infusion raised the plasma concentration of magnesium (PMg) from 0.64 +/- 0.05 to 3.06 +/- 0.27 mM and doubled magnesium reabsorption. The infusion of acetazolamide at high PMg reduced bicarbonate reabsorption by 41 +/- 3% and magnesium reabsorption by 31 +/- 16%. When plasma pH was reduced to 7.04 +/- 0.02 and increased to 7.83 +/- 0.02 by altering PCO2 at a constant plasma bicarbonate concentration of 31.2 +/- 0.8 mM, magnesium and bicarbonate reabsorption were correlated (r = 0.82). The infusion of mannitol, which acts by reducing passive solute transport without affecting bicarbonate reabsorption, halved magnesium reabsorption. By combining mannitol and acetazolamide infusions, only 6 +/- 4% of the filtered magnesium was still reabsorbed. These results indicate that the reabsorption of magnesium remaining after the infusion of ethacrynic acid and after raising PMg varies with changes in PCO2 and is inhibited by the infusion of acetazolamide and mannitol as expected for bicarbonate-dependent passive reabsorption.

Pathogenetic relationships between renal tubular acidosis and sodium metabolism alterations in liver cirrhosis.

5 cirrhotic patients with latent distal renal tubular acidosis (RTA) and 5 cirrhotic patients with normal distal acidification ability were studied. All the patients were maintained on a 80 mEq/day sodium diet for at least 5 days before the study. Only 2 of the 5 patients with RTA showed a reduced daily sodium excretion while the 3 other patients with RTA had a normal natriuresis. Acidification ability was retested in all the patients after increasing sodium distal delivery by intravenous administration of ethacrynic acid. Some hours after the maximal natriuretic effect induced by ethacrynic acid, a normalization of the acidification test was seen in all patients with RTA. These findings support the concept that although sodium metabolism alterations are not the only factor in the pathogenesis of RTA in liver cirrhosis, reduced availability of sodium at the distal tubule may impair tubular acidification, probably by influencing the distal transtubular potential difference.

Effects of diuretics on inner medullary hemodynamics in the dog.

Although the hemodynamic effects of diuretics have been studied extensively, their effects on inner medullary blood flow remain unknown. In the present study, renal hemodynamics, including papillary plasma flow measured by the albumin accumulation technique, and associated alterations in papillary tissue solute content were determined in anesthetized, hydropenic dogs and during euvolemic diuresis induced by furosemide (3 mg/kg plus 2 mg/kg per hr, iv), ethacrynic acid (3 mg/kg plus 2 mg/kg per hr, iv) or chlorothiazide (10 mg/kg plus 10 mg/kg per hr, iv). Renal blood flow increased significantly after furosemide and ethacrynic acid and decreased significantly after chlorothiazide. Sixty minutes after diuretic administration, papillary plasma flow was 10.8 +/- 1.0 (mean +/- SE) in six furosemide- and 11.3 +/- 2.6 ml/min per 100 g in six ethacrynic acid-treated dogs, both significantly lower than in eight normal or eight chlorothiazide-treated dogs [26.4 +/- 2.6 and 26.7 +/- 2.7 ml/min per 100 g, respectively (P less than 0.01)]. A similarly low papillary plasma flow was also noted 10 minutes after diuretic administration in five furosemide and four ethacrynic acid dogs (13.6 +/- 2.3 and 13.4 +/- 1.8 ml/min per 100 g, respectively). In furosemide and ethacrynic acid dogs, papillary osmolality and sodium content were significantly lower than those in normal or chlorothiazide dogs. In normal and chlorothiazide dogs, papillary sodium content was similar, with a significantly reduced papillary osmolality in the latter. At the time papillary plasma flow was measured, extracellular fluid volume was similar among the four groups of dogs; however, plasma renin activity increased significantly in furosemide and ethacrynic acid dogs (P less than 0.01) and remained unchanged in normal and chlorothiazide dogs. Furthermore, papillary plasma flow was restored to normal (25.3 +/- 3.9 ml/min per 100 g) in five dogs in which furosemide was infused during angiotensin II blockage with saralasin, despite a similar diuresis and natriuresis as the other furosemide group. These data demonstrate that after administration of furosemide, ethacrynic acid and chlorothiazide, regulation of papillary plasma flow is independent of renal blood flow, and suggest that angiotensin II may play a role in the reduced papillary plasma flow in furosemide and ethacrynic acid dogs.

Functional and morphological findings of endolymphatic sac.

After obliteration of endolymphatic sac and duct, no significant alteration in d.c. potential, K+ activity or protein content during the development of endolymphatic hydrops could be observed. The K+ activity of endolymphatic sac was only one-ninth of that in the cochlear part of the endolymph. After injection of Thorotrast into the endolymphatic sac, aggregated particles were found in the cochlear endolymph 2 days later. Ethacrynic acid (60 mg/kg) caused a decrease in K+ activity in the cochlear endolymph, but an increase in the endolymphatic sac. Intercellular edema was observed both in stria vascularis and in endolymphatic sac by light and electronmicroscopy after ethacrynic acid administration. These results suggest the existence of an active transport mechanism in the endolymphatic sac epithelium.

Effect of Na-K-ATPase inhibition on hydrogen ion and potassium secretion.

The purpose of the present study was to examine whether in vivo inhibition of renal Na−K-ATPase affects renal H+ and potassium (K) secretion. Infusion of digoxin, furosemide, or ethacrynic acid into one renal artery of HCO3 loaded dogs caused similar increases in urine flow, fractional Na and Cl excretion, and fractional water excretion. Glomerular filtration rate and urinary HCO3 concentration fell comparably in all experiments. Maximal HCO3 reabsorption was not depressed by any of the drugs infused, however only digoxin inhibited renal Na−K-ATPase activity. Furthermore, unilateral digoxin infusion resulted in a marked depression in the urine to bloodpCO2 gradient (U-BpCO2) and prevented the rise in fractional K excretion secondary to HCO3 infusion observed in the contralateral control kidney. At all urinary HCO3 concentrations, U-BpCO2 was significantly higher in urine obtained from furosemide or ethacrynic acid infused kidneys than in urine obtained from digoxin infused kidneys. In addition, furosemide or ethacrynic acid administration markedly enhanced fractional K excretion in both kidneys. The systemic infusion of tris(hydroxymethyl)aminomethane (THAM; pK 8.0) failed to return U-BpCO2 in the digoxin infused experimental kidneys to control levels, whereas THAM caused a marked rise in U-BpCO2 in the control kidney. These data demonstrate that the in vivo inhibition of renal Na−K-ATPase by digoxin causes a defect in the secretion of both H+ and K. This defect likely results from the dissipation of the Na dependent lumen negative potential difference (PD) by digoxin, since a lumen negative PD favors both H+ and K secretion in the collecting duct. Furthermore, these data do not support the notion that furosemide or ethacrynic acid affect tubular transport through the inhibition of renal Na−K-ATPase activity.

Diuretics, hepatic and thoracic duct lymph flows in the dog.

1. Simultaneous thoracic duct and hepatic lymph flows were measured in 29 mongrel dogs before and after the intravenous administration of mannitol, ethacrynic acid, frusemide and chlorothiazide in separate experiments. 2. Thoracic duct lymph flow increased significantly after each diuretic agent was administered. 3. Hepatic lymph flow increased only after ethacrynic acid and mannitol administration. Frusemide and chlorothiazide did not alter hepatic lymph flow. 4. These data show that increases in thoracic duct lymph flow after ethacrynic acid and mannitol arise partly from the liver, as well as from other organs.

Ototoxic effects of the interaction between kanamycin and ethacrynic acid. Cochlear ultrastructure correlated with cochlear potentials and kanamycin levels.

The effects of the interaction between kanamycin (KAN) and ethacrynic acid (EA) on the ultrastructure of the guinea pig cochlea were studied 3, 4, 6, and 24 hours following administration of EA (40 mg/kg) to animals pretreated 2 h earlier with KAN (400 mg/kg). Appropriate saline (SAL) controls were included giving 4 treatments: KAN/EA, KAN/SAL, SAL/EA and SAL/SAL. The outer hair cells of the organ of Corti showed nuclear and plasma membrane changes at 3 h and were completely destroyed at 24 h. The inner hair cells were unaffected. Severe swelling was seen in the stria vascularis of both KAN/EA and SAL/EA animals at 3 h and was gone by 24 h. KAN/EA had a greater effect on the stria than had SAL/EA. These results were consistent with the time course of the effect of the drugs on the a.c. and d.c. endocochlear potentials. KAN concentrations in perilymph were unaffected by treatment with EA.

The effects of ethacrynic acid upon the potassium concentration in guinea pig cochlear fluids

After i.v. injection of 50 mg/kg ethacrynic acid (EA), potassium concentration in the endolymph (K e +) measured with K +-specific microelectrodes decreases by 10 mM at the most and endocochlear potential falls to negative values. Potassium concentration in the perilymph (K p +) generally does not change, but sometimes a transient decrease in K p + level of about 0.5 mM was observed, presumably due to the electrogenic effect of the time-related decrease of the endocochlear potential. When anoxia is induced approximately 120 min after EA administration, K e + slowly decreases. The decrease in K e + 50 min after the arrest of ventilation is smaller when compared with the K e + anoxic decrease without preceding EA administration. The endocochlear potential, which falls to negative values during anoxia after EA administration, does not return to the zero level as in the case when only anoxia is applied. Similarly, during anoxia, which follows EA administration, the perilymphatic K e + concentration increases more slowly than in the case when only anoxia is introduced. It is assumed from the results that EA abolishes activity of the positive electrogenic K + pump and reduces the passive permeability of the walls of the cochlear duct to the potassium ions.

Reversible and irreversible changes of the stria vascularis. An evaluation of the effects of ethacrynic acid separately and in combination with atoxyl.

The morphological changes in the cochlea following administration of ethacrynic acid occur initially in the stria vascularis of the basal coils as an increased intracellular vesiculation of the marginal cells followed by inter- and intracellular oedema in the intermediate cell layer. The combined administration of ethacrynic acid and atoxyl (individual doses) can cause irreversible damage to the cochlear hair cells and the stria vascularis, while the administration of each of them separately in the same low dose did not cause hair cell degeneration or persistent morphological changes of the stria vascularis. An increased penetration of atoxyl into the cochlea is likely to occur due to the ethacrynic acid-induced changes in the permeability of the endolymphatic partition so that the earlier known penetration of atoxyl into the cochlea is increased.

Histochemical Study on Pathogenesis of the Inner Ear Damage Caused by Ethacrynic Acid and Furosemide

Morphologic changes in the capillary network of the stria vascularis of guinea pigs were investigated on the surface specimens of the spiral ligaments after the superficial blood vessels of the scalas were stained with benzidine. It was demonstrated that multiple narrowing of the capillary lumen and occasional ischemia occurred in the capillary network of the stria vascularis immediately after intravenous administration of ethacrynic acid (80mg/kg) or furosemide (100mg/kg). These changes were recovered rapidly in guinea pigs receiving furosemide, but slowly in the animals treated with ethacrynic acid. On the other hand, intracochlear perfusion with histochemical reaction solution containing Nitro-blue tetrazolium (Nitro-BT, 0.05%) and phosphate buffer (pH7.4) was carried out immediately after decapitation to demonstrate the alterations in supravital reduction at the CoQ-level of the electron transfer system of the surviving hair cells of the spiral organ. Microscopic observation in the surface specimens of the spiral organ revealed that supravital reduction of Nitro-BT occurred prominently in the inner hair cells, but was impaired considerably in the outer hair cells immediately after intravenous injection of ethacrynic acid (80mg/kg) or furosemide (100mg/kg). However, the impaired reduction in the outer hair cells recovered almost completely 3 hours later in guinea pigs receiving furosemide. On these surface specimens, the body of the outer hair cells became swollen in association with disturbance of the supravital reduction of the Nitro-BT. These findings suggest that these damages in the outer hair cells may be caused by primary injury of the membrane ATPase by the diuretics, and these damages were independent of intercellular edema of the stria vascularis. The latter change may be responsible for the narrowing and compression of the capillary lumen in the stria vascularis and ischemia.