Chronopharmacological study of furosemide; (V). Influence of pretreatment with 6-hydroxydopamine

Decrease in the time-dependent difference in urinary excretion of furosemide with age

The influence of age on the time-dependent difference in urinary excretion of furosemide, a loop diuretic agent, was examined in this longitudinal study. Male Wistar rats were maintained under conditions of light from 07:00 to 19:00 h and dark from 19:00 to 07:00 h. Furosemide (30 mg/kg) was given orally at 12:00 h (day trial) or 00:00 h (night trial) to rats at 3 months of age, and urine was collected for 8 h after dosage. Thereafter, the identical protocol was repeated using the same animals at 6, 9, 12, 15, 18, and 21 months of age. The urinary excretion of furosemide was significantly greater in the day than in the night trial at 3 months of age. Such a time-dependent difference was observed for up to 15 months, but disappeared at 18 and 21 months of age. The time-dependent difference in urinary excretion of furosemide (day trial - night trial) decreased gradually throughout the observation period of the study. These results suggest that the time-dependent difference in the urinary excretion of furosemide diminishes during the aging process and disappears by 18 months of age in male Wistar rats.

Daily variation in the urinary excretion of furosemide in young and aged rats

We have recently demonstrated that the time-dependent difference in urinary excretion of furosemide, a loop diuretic, diminishes during the aging process and disappears by 18 months of age in rats. The present study was undertaken to examine whether the amplitude of the daily variations in the urinary excretion of furosemide or their pattern, or both, are influenced in aged animals. Young (3 months of age) and aged (30 months of age) Wistar rats were maintained under conditions of light from 7 am to 7 pm and dark from 7 pm to 7 am. Furosemide (30 mg/kg) was given orally at 4 am, 8 am, 12 am, 4 pm, 8 pm or 12 pm. Urine was collected for 8 hours after furosemide administration and urinary excretion of furosemide was determined. There were significant daily variations in the urinary furosemide and the urine volume with the peak at 8 am and the trough at 12 pm in both groups of rats. The differences in these parameters between the 8 am and 12 pm trials were significantly smaller in the aged than in the young rats. These results suggest that the age-related alteration in the time-dependent phenomenon of furosemide is caused by the decreased amplitude of the daily variation in the urinary furosemide excretion and its diuretic effect.

Time-dependent change in the toxic effects of amikacin on renal functions

The present study was undertaken to examine whether there was a time-dependent change in the toxic effects of amikacin, an aminoglycoside, on renal functions. Male Wistar rats were maintained under conditions of light from 7 am to 7 pm and dark from 7 pm to 7 am. Amikacin (1.2 g/kg) was injected intraperitoneally to animals at 4 am, 10 am, 4 pm or 10 pm. Glomerular function estimated by creatinine clearance (Clcr) and tubular function estimated by urinary excretion of a loop diuretic, furosemide, which was excreted in urine mainly by tubular secretion, were determined before and 24 hours after amikacin injection. The values of these parameters were reduced by amikacin at each observation point. The magnitude of these decrements was greatest at 4 pm both for Clcr and urinary furosemide excretion. These results suggest that the toxic effects of amikacin on renal glomerular and tubular functions vary with its time of administration.

Effects of heparin on the inhibitory activities of human urinary trypsin inhibitor (ulinastatin) on trypsin, chymotrypsin and leukocyte elastase

Effects of heparin on the inhibitory activities of human urinary trypsin inhibitor (ulinastatin) on trypsin, chymotrypsin and leukocyte elastase were studied. Heparin per se neither influenced the enzymatic activities nor changed the mode of inhibition of ulinastatin on the enzymes. In the presence of heparin, inhibitory effects of ulinastatin on trypsin were enhanced, whereas its effects on chymotrypsin and elastase were attenuated. These results suggest that the two functional domains in ulinastatin are differently affected by heparin.

Influence of clorgyline treatment on chronopharmacology of furosemide in rats

Circadian variations in the adrenergic nervous system have been reported to be altered by chronic treatment with clorgyline, a monoamine-oxidase inhibitor. In the present study, the influence of clorgyline on the chronopharmacology of furosemide, a loop diuretic agent, was examined in rats maintained under conditions of light from 7 am to 7 pm and dark from 7 pm to 7 am. Clorgyline (4 mg/kg/day) or its vehicle alone was infused subcutaneously by osmotic minipumps for 14 days. Furosemide (30 mg/kg) was given orally at 12 am [noon (N)] or 12 pm [midnight (M)]. Urine was collected for 8 hours after the agent, and urinary excretions of sodium and furosemide were determined. Urine volume and urinary excretions of sodium and furosemide were significantly greater at 12 N than at 12 M in the vehicle-infused group of rats. However these administration time-dependent changes in the effects of furosemide and its urinary excretion disappeared in the clorgyline-infused animals. These results suggest that the mode of the diurnal variation in the effects of furosemide is altered by chronic treatment with clorgyline. As chronic clorgyline is considered to disturb the adrenergic nervous system, the present findings are compatible with the hypothesis that this system is involved in the mechanism responsible for the time-dependent change in the effects of furosemide.

Daily variation in the effects of furosemide in rats

Daily variation in the effects of furosemide, a loop diuretic agent, was examined in Wistar rats maintained under conditions of light from 7 a.m. to 7 p.m. and dark from 7 p.m. to 7 a.m. Furosemide (30 mg/kg) was given orally at 12 p.m., 4 a.m., 8 a.m., 12 a.m., 4 p.m. or 8 p.m. Urine was collected for 8 hr after furosemide administration, and urinary excretions of sodium and furosemide were determined. There were significant daily variations in the urine volume and urinary excretions of sodium and furosemide with a peak at 8 a.m. and a trough at 12 p.m. Significant correlations were observed between the urinary amount of furosemide and its diuretic effects (urine volume and urinary sodium excretion). These results suggest that the diuretic effects of furosemide show daily variations which are, at least in part, caused by the daily variation in the urinary excretion of furosemide.

Chronopharmacology of furosemide in the elderly

The authors have previously reported the time-dependent change in the diuretic effects of furosemide, a loop diuretic agent, in young and middle-aged subjects. The current study was undertaken to examine an influence of aging on this chronopharmacologic phenomenon. Ten milligrams furosemide was given intravenously to 12 elderly subjects (greater than 70 years of age) at 9:00 AM (day trial) or at 9:00 PM (night trial) by a cross-over design. One-hour urine samples were collected for 3 hours after each administration, and urine volume and urinary excretions of sodium and furosemide were determined. Urine volume and urinary sodium excretion increased after furosemide administration. Contrary to the findings in the young and middle-aged subjects, no significant differences were observed in these parameters at any observation period between the day and night trials in the elderly subjects. Urinary furosemide excretion of the day and night trials did not significantly differ. These results suggest that the chronopharmacologic profiles of furosemide are altered in the elderly.

Influence of DOCA treatment on administration-time-dependent changes in the effects of furosemide in saline-loaded rats

We have previously found that the administration-time-dependent change in the effects of furosemide, a loop diuretic agent, is observed in normal rats. The present study was undertaken to examine whether an alteration in this phenomenon occurs in rats with DOCA-saline hypertension. Unilateral nephrectomized rats were divided into three groups. The first group (DOCA-saline) received a 50 mg DOCA tablet intraperitoneally and drank 1% NaCl solution. The other two groups were given sham operations. A 1% NaCl solution was given as drinking water to the second group (control-saline), while tap water was given to the third group (control-water). Furosemide (30 mg/kg) was given orally to each group at 12 a.m. or 12 p.m. Urine was collected for 8 hours after the agent, and urinary excretion of sodium and furosemide were determined. Urine volume and urinary excretion of sodium and furosemide following the agent were significantly greater at 12 a.m. than at 12 p.m. in the control-water and control-saline groups. However, the administration-time-dependent changes in these parameters disappeared in the DOCA-saline rats. These results suggest that the mode of the administration-time-dependent changes in the effects of furosemide is altered in the DOCA-saline hypertensive rats.

Influence of renal denervation on chronopharmacology of furosemide in rats

Our previous studies have suggested that the adrenergic nervous system is involved in the mechanism responsible for the time-dependent change in the urinary excretion of furosemide in rats. To examine a potential role of renal nerves in this phenomenon, renal denervation or sham operation was performed using unilaterally nephrectomized rats. Furosemide (30 mg/kg) was given orally at 12 am or 12 pm. Urine was collected for 8 hours after furosemide dosing, and urinary excretions of furosemide and sodium were determined. Urinary furosemide excretion and diuretic effects of the agent (urine volume and urinary sodium) were significantly greater at 12 am than at 12 pm in the sham-operated group of rats. However these administration time-dependent changes in urinary furosemide and its diuretic effects disappeared in the renal-denervated group of animals. These results suggest that the renal nerves contribute to the time-dependent changes in the urinary excretion of furosemide and its subsequent diuretic effects.

Chronopharmacological study of furosemide; (IX). Influence of continuous norepinephrine infusion

Our previous studies have suggested that the adrenergic nervous system is involved in the mechanisms responsible for the time-dependent changes in the effects of furosemide in rats. To examine this hypothesis further, norepinephrine (150 micrograms/kg/hr) or its vehicle alone was infused subcutaneously by osmotic minipumps. Furosemide (30 mg/kg) was given orally at 12 am or 12 pm. Urine was collected for 8 hours after the agent, and urinary excretions of sodium and furosemide were determined. Urine volume and urinary excretion of sodium and furosemide were significantly greater at 12 am than at 12 pm in the vehicle-infused group of rats. However these administration-time-dependent changes in the effects of furosemide and its urinary amount disappeared in the norepinephrine-infused group of animals. Since chronic norepinephrine infusion is considered to disturb the axis of adrenergic nervous system, these data support the hypothesis concerning the mechanisms of this chronopharmacological phenomenon of furosemide.

Chronopharmacological study of furosemide; (VIII) influence of feeding restriction

We have previously reported that a time-dependent variation is observed in the diuretic effect of furosemide and the light-dark cycle is a potent zeitgeber for this chronopharmacological phenomenon of the agent in rats. The present study was undertaken to examine whether a time of food intake is another zeitgeber for this event. In study I, rats were maintained with free access to food for 3 weeks. Furosemide (30 mg/kg) was given orally at 12 am or 12 pm. Urine was collected for 8 hours after the agent and urinary excretion of sodium and furosemide were determined. Thereafter, these rats were maintained under a daytime-restricted feeding schedule (9 am-11 am) for 3 weeks (study II) and a night-time-restricted feeding schedule (9 pm-11 pm) for 3 weeks (study III). The identical protocol of study I was repeated at the end of study II and III. Diuretic effect of furosemide and its urinary excretion were significantly greater at 12 am than at 12 pm in study I and III. However such an administration time-dependent change in the effect of furosemide and its urinary amount disappeared in study II. These data indicate that a time of food intake is another potent zeitgeber for the time-dependent variation in the diuretic effect of furosemide.

Chronopharmacological study of furosemide; (VI). Influence of prolonged exposure to continuous light

We have previously reported that a time-dependent variability is observed in the diuretic effects of furosemide in rats. The present study was undertaken to examine the influence of prolonged exposure to continuous light on chronopharmacological profiles of furosemide in Wistar rats. In study I, rats were maintained for more than 2 weeks under conditions of light (0700-1900 hrs) and dark (1900-0700 hrs) (L-D). Furosemide (30 mg/kg) was orally given at 1200 hrs or at 2400 hrs. Urine was collected for 8 hours after the drug and urinary excretion of sodium and furosemide were determined respectively. Thereafter, these rats were exposed to continuous light (L-L) for the next 4 weeks, and were again maintained under the L-D cycle. The identical trial of study I was repeated at the end of the L-L (study II) and the second L-D (study III) conditions. Urine volume and urinary excretion of sodium and furosemide following the drug were significantly greater at 1200 hrs than at 2400 hrs under conditions of L-D (study I and III). However these administration time-dependent changes in the effects of furosemide and its urinary amount disappeared with L-L condition (study II). These findings indicate that the mode of the time-dependent changes in the effects of furosemide is altered by prolonged exposure to continuous light.