Renal clearance of lomefloxacin is decreased by furosemide

The interaction between lomefloxacin, a new quinolone, and furosemide, a loop diuretic, has been examined. Oral lomefloxacin 200 mg and furosemide 40 mg were given together or separately to 8 healthy subjects, and blood and urine samples were obtained over the following 12 h. The plasma concentrations of lomefloxacin following coadministration with furosemide were higher than after lomefloxacin alone and its AUC was increased, and its total and renal clearances were decreased. No change in the pharmacokinetics of furosemide was found after coadministration of lomefloxacin. As quinolones and furosemide are reported to be excreted in urine by the renal tubular anion transport system, the present results suggest that the renal tubular secretion of lomefloxacin is diminished by furosemide. It is not clear whether this pharmacokinetic interaction might be clinically important.

Comparison of the pharmacokinetics, pharmacodynamics, and safety of oral (Catapres) and transdermal (M-5041T) clonidine in healthy subjects

The pharmacokinetic as well as pharmacodynamic properties of a transdermal clonidine, M-5041T (M) and its safety were compared with those of oral clonidine, Catapres (Nippon Boehringer Ingelheim, Hyogo, Japan). One patch of M containing 6 mg of clonidine was applied on the right chest for 3 days or one tablet of Catapres (.075 mg) was given orally every 12 hours for 3 days in eight healthy subjects. The study was conducted by a crossover design with 14 to 16 days' interval between the cross-over. Blood and urine samples for clonidine concentration were obtained, and blood pressure (BP) was measured for a 168-hour period after application of M and for a 96-hour period after initiation of Catapres therapy. Plasma concentration of clonidine increased gradually after application of M and decreased gradually after removal, whereas this parameter increased rapidly during the absorption phase and decreased rapidly in the elimination phase after each dosage of Catapres. Elimination half-life of clonidine after removal of M was significantly greater than that after the final dosage of Catapres. No significant difference was observed in maximum plasma concentration or area under the plasma concentration-time curve between the two trials. The BP lowering effects of M and Catapres did not differ significantly. Adverse symptoms occurred more frequently during Catapres therapy than during treatment with M. Most of these symptoms were observed when plasma clonidine concentration was relatively higher in each trial. These results suggest that M is effective for the treatment of hypertension with a lower incidence of adverse symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Velocity of Oxygen Transfer and Erythrocyte Rheology

Rheological properties of erythrocytes relate to the oxygen transfer to tissues in microcirculation. Erythrocytes deform by externally applied physical forces. The deformability modifies the pathway of oxygen diffusion inside the microvessel. The rate of oxygen release from flowing erythrocytes in a single microvessel is determined spectrophotometrically under the microscope.

Effect of interferon-gamma on nitric oxide hemoglobin production in endotoxin-treated rats and its synergism with interleukin 1 or tumor necrosis factor

We studied the in vivo effect of interferon-gamma (IFN-gamma) on nitric oxide (NO) generation. ESR spectra of nitric oxide hemoglobin (HbNO) appeared after a lag time of 2h in the blood of rats treated with Escherichia coli lipopolysaccharide (LPS). IFN-gamma enhanced LPS-induced HbNO formation in rats without modifying the time lag, although IFN-gamma alone did not induce HbNO formation. The plasma nitrate concentration was approximately one order of magnitude higher than the HbNO concentration. On treatment with LPS alone, the amount of tumor necrosis factor (TNF) released decreased after 2 h. Simultaneous addition of IFN-gamma and LPS increased TNF release for at least 8 h. Interleukin 1 (IL-1) release was detected only at 2 h in both groups. We also investigated the in vivo interactions of these cytokines. TNF plus IL-1 induced the greatest HbNO generation, followed by TNF plus IFN-gamma, and then IL-1 plus IFN-gamma. These results suggest that increase of TNF release by IFN-gamma plays a key role in NO generation in LPS-treated rats.

Intravital microreflectometry of individual pial vessels and capillary region of rat

A microscopic reflectance spectrophotometer was constructed to obtain the spectra of single pial vessels and of a region containing only capillaries (capillary region). The difference in the oxygen saturation (SO2) of hemoglobin between the regional arteriole and venule [R(A - V)] and that between the regional arteriole or capillaries [R(A - C)] were calculated. The reduction of cytochrome aa3 was also estimated in the capillary region. This method was applied to the brain surface of spontaneously breathing rats subjected to hypoxic and anemic hypoxia. On decreasing the inhaled O2 from 100 to 15%, elevation of R(A - V) and R(A - C) with slight arteriolar dilatation (though statistically not significant) was observed. Below 10% O2 (especially at 4 and 3% O2), the R(A - V) and R(A - C) decreased in spite of significant arteriolar dilatation with progressive reduction of cytochrome aa3, indicating suppression of oxygen transport to mitochondria. In the case of hemodilution down to 37% hematocrit (Ht), elevation of R(A - V) and R(A - C) occurred with a slight tendency toward arteriolar dilatation. Below 32% Ht, the R(A - V) decreased but the R(A - C) remained steady, while reduction of cytochrome aa3 progressed. Altogether, the SO2 in the capillary region decreased and the reduction of cytochrome aa3 progressed with the decline of arteriolar O2 supply in both hypoxic and anemic hypoxia.

Reactive oxygen species involved in phenazine-methosulfate-induced rat lens opacification. An experimental model of cataract

The excised rat crystalline lens opacified when incubated aerobically with phenazine methosulfate, but no opacification was observed under anaerobic conditions. Morphological studies revealed development of opacification in the cortex. The opacification resembled that often seen in the early period of senile cataract as well as in naphthalene-induced and UV cataract. Both an increase in hydration and in electrolyte imbalance accompanied this opacification. Na,K-ATPase activity of the opacified lens was found to decrease. In order to investigate if activated oxygen is involved in these processes, we conducted an electron spin resonance study by means of a spin trapping technique. When the lens homogate was incubated with phenazine methosulfate, OH radicals were generated under aerobic but not under anaerobic conditions. Reduced pyridine nucleotides must be involved in the process, because the mixture of nicotinamide adenine dinucleotide phosphate [NAD(P)] and phenazine methosulfate did not generate OH radicals, but the mixture of NAD(P)H and phenazine methosulfate generates OH radicals, indicating that reduced phenazine methosulfate was involved in the OH radical generation. Probably, the generated OH radicals inactivated Na,K-ATPase residing in the epithelium of the lens, which eventually caused opacification of the lens. The present experiment system may be used for the elucidation of lens opacification (cataract) involved with reactive oxygen species.

Influence of application site of a new transdermal clonidine, M-5041T, on its pharmacokinetics and pharmacodynamics in healthy subjects

Influence of application site of a new transdermal clonidine, M-5041T(M), on its pharmacokinetics and pharmacodynamics were evaluated in eight human subjects. One patch of M-6 mg was applied for 3 days on the right chest (first trial), on the left arm (second trial), and on the upper abdomen (third trial). Blood samples for clonidine concentration were taken, and blood pressure (BP) was measured for a 120-hour postapplication period. Plasma concentrations of clonidine increased after application of M in each trial. This parameter in the second trial was significantly greater than that of the first and third trials. The values of maximum plasma concentration and area under the plasma concentration-time curve in the second trial were greater than those of other trials, but the differences did not reach significance. The BP-lowering effect of M in the second trial was significantly greater than that of the third trial. These results suggest that the plasma concentrations of clonidine after application of M and its hypotensive effect are affected by the site of application in human subjects.

Pharmacokinetics and pharmacodynamics of a new transdermal clonidine, M-5041T, in healthy subjects

The pharmacokinetic as well as the pharmacodynamic properties of a new transdermal clonidine, M-5041T (M), and its safety were evaluated after single and repeated applications. In the single-application study, one patch of M (4 mg-->6 mg-->8 mg) was applied for 3 days in eight healthy subjects. In the repeated-application study, first (0-72 hours), second (72-144 hours), and third (144-216 hours) patches of M 6 mg were applied in seven healthy subjects. In the single-application study, plasma clonidine concentration increased in a dose-dependent manner after application of M. Maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) increased in a dose-dependent manner, but the difference did not reach significance. Time to maximum concentration, elimination half-life, and total and renal clearance did not differ significantly among three trials. Blood pressure (BP) decreased gradually after application of each dose of M. The BP-lowering effect of M 8 mg was greater than that of M 4 mg and 6 mg. Adverse effects such as erythema and drowsiness were reported in some subjects. No subject had to be withdrawn from the study because of the appearance of adverse effects. In the repeated-application study, plasma concentration of clonidine increased up to 48 hours after application of first patch, and thereafter remained within a relatively narrow range until removal of third patch. The Cmax and AUC did not differ significantly among three trials. Blood pressure during an active period decreased significantly during treatment with M, whereas BP at midnight did not change significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of diltiazem and cimetidine on theophylline oxidative metabolism

The effect of diltiazem or cimetidine pretreatment on the inhibition of theophylline oxidative metabolism was investigated in nine healthy male nonsmokers. Diltiazem 60 mg, cimetidine 400 mg, or placebo was given orally three times daily for 3 days in a randomized three-way crossover manner. Both diltiazem and cimetidine pretreatment decreased the mean theophylline clearance (0.702 on placebo versus 0.641 on diltiazem, P < .05, and 0.542 mL/minute/kg on cimetidine, P < .01), resulting in prolonged mean theophylline half-life (7.58 on placebo versus 8.59 on diltiazem, P < .05, and 10.08 hours on cimetidine, P < .01) with no change in volume of distribution. The mean metabolic clearances for three major theophylline metabolites, 1-methyluric acid (1-MU), 1,3-dimethyluric acid (1,3-DMU), and 3-methylxanthine (3-MX), were reduced significantly by cimetidine (28%; P < .05, 32%; P < .01, and 33%; P < .01, respectively). Conversely, diltiazem significantly reduced only the mean metabolic clearance of 1,3-DMU by 21% (P < .05) without changes in that of 1-MU or 3-MX. These results suggest that cimetidine inhibited both N-demethylation and 8-hydroxylation of theophylline, whereas diltiazem exerted little influence on N-demethylation in spite of inhibition in 8-hydroxylation.

Spin trapping study of superoxide production in ferrous ion oxidation

The oxidation of Fe2+ was investigated by electron paramagnetic resonance (EPR) spin trapping techniques with N-t-butyl-alpha-phenylnitrone (PBN) and dimethyl sulfoxide. Under pure oxygen, the spin adduct PBN/.OCH3 was rapidly generated by the addition of Fe2+ (0.2-1.2 mM) into phosphate buffer containing ethylenediaminetetraacetate (EDTA), dimethyl sulfoxide and PBN at pH 7.4, but it decayed. The decay process of PBN/.OCH3 consists of two components. The fast decay was dependent on Fe2+ concentration. Another was due to destruction of the spin adduct by superoxide anion (.O2-), because superoxide dismutase (SOD) markedly prevented the decay. Catalase decreased the yield of PBN/.OCH3. When Fe(3+)-EDTA and ascorbate were used instead of Fe(2+)-EDTA, similar phenomena were detected. These results demonstrate that Fe2+ reacts with O2 to generate .O2-, then H2O2, which produces .CH3 by the reaction with Fe2+ and dimethyl sulfoxide. The .OCH3 radical results from the reaction between .CH3 and O2. The adduct PBN/.OCH3 decays by the reaction with Fe2+ and .O2-.

The rate of oxygen release from single sinusoid of rat liver, determined by microspectroscopy

The rate of oxygen release from single hepatic sinusoid of rat was determined. A scanning spectrophotometer, equipped with a grating and two photoncounters, was connected to a microscope with light-guides, and absorption spectra (450-650 nm) were obtained simultaneously at two microspots (10 microns diameter) on single sinusoid. The concentration ([Hb]) and oxygen saturation (SO2) of hemoglobin were calculated from the spectra. Reference transmittance was obtained at neighbouring hepatocytes. The erythrocyte velocity was measured by dual-spots cross-correlation method using two photomultipliers connected to the microscope with two light-guides. The gradient in SO2 was observed along each sinusoid, due to oxygen release from flowing erythrocytes to hepatocytes. The rate of oxygen release per unit surface area was 0.24 +/- 0.14(n = 14)nmoles O2/cm2/sec, which was calculated from [Hb], difference in SO2 between the spots at up- and down-stream, erythrocyte velocity, two spot's distance and sinusoidal diameter. The rates of O2 release depended on sinusoidal diameter and sinusoidal blood flow.

Differences of chronopharmacokinetic profiles between propranolol and atenolol in hypertensive subjects

Previous studies have shown that the absorption rate of a lipophilic, but not hydrophilic, agent is faster after the night dosage than after the morning dosage in nocturnal rodents. The present study examines whether such a difference in chronopharmacokinetic profiles between lipophilic and hydrophilic agents also exists in humans. Propranolol (20 mg), a lipophilic beta-blocker, or atenolol (50 mg), a hydrophilic beta-blocker, was given orally to 13 hypertensive patients at 9:00 AM (day trial) or 9:00 PM (night trial) by a crossover design. Plasma concentrations of propranolol and its metabolites, 4-hydroxypropranolol and naphthoxylactic acid, and atenolol were determined just before and at 0.5, 1, 1.5, 2, 3, 4, 6, 12, and 24 hours after treatment. Maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) of propranolol in the day trial were significantly greater than those in the night trial. Time to maximum plasma concentration (tmax) was significantly shorter in the day trial. No significant difference was observed in the elimination half-life between the two trials. There were similar administration time-dependent changes in the Cmax for 4-hydroxypropranolol and naphthoxylactic acid. On the other hand, although the Cmax of atenolol was greater and its tmax was shorter in the day trial, the differences did not reach significance. These results suggest that propranolol, but not atenolol is absorbed more rapidly after the morning dosage than after the night dosage. Based on these findings, the authors speculate that the absorption rate of a lipophilic, but not hydrophilic, agent is faster after the morning dosage than after the night dosage in humans.

Influence of alpha-receptor blockade on the time-dependent change in the effect of furosemide

Influence of alpha-receptor blockade on the time-dependent change in the effect of furosemide (a loop diuretic agent) was examined. Furosemide (30 mg/kg) was given orally to the doxazosin (an alpha 1-blocker)- or vehicle-treated rats at 12 AM or 12 PM. Urine volume and urinary excretions of of sodium and furosemide for 8 hr were significantly greater at 12 AM than at 12 PM in the vehicle-treated animals. However, such time-dependent changes in these parameters disappeared in the doxazosin-treated rats. These results suggest that the alpha 1-receptor-mediated stimuli are involved in the mechanism of the time-dependent change in the effect of furosemide.

Spin trapping of superoxide released by opsonized asbestos from human promyelocytic leukemia cell line, HL60

By ESR using 5,5-dimethyl-1-pyrroline-1-oxide as a spin trap, superoxide (O2-) production was proved upon stimulation of dimethyl sulfoxide-differentiated HL60 by crocidolite opsonized with fresh or refrigerated serum, as well as by phorbol myristate acetate (PMA). Crocidolite, unopsonized or opsonized with frozen-thawed or heat-inactivated serum, did not induce O2- release. Addition of iron chelators or superoxide dismutase inhibited O2- release completely. Neither undifferentiated nor PMA-differentiated HL60 released O2- upon stimulation with opsonized crocidolite.

Influence of lisinopril on urinary electrolytes excretion after furosemide in healthy subjects

It has been reported that the urinary excretions of chloride (Cl), potassium (K), and magnesium (Mg), but not sodium (Na), after furosemide, a loop diuretic, were decreased by pretreatment with lisinopril, an ACE inhibitor in hypertensive subjects. The electrolytes disturbance induced by furosemide might be ameliorated by lisinopril. The present study re-examines this potential drug interaction in healthy subjects. Lisinopril (20 mg) or its matching placebo was given orally using a double-blind, crossover design. Four hours after lisinopril administration, furosemide (20 mg) was injected intravenously and urine was collected during the following intervals: 0-0.5, 0.5-1, 1-1.5, 1.5-2, 2-3, 3-4, and 4-6 hours. Blood samples for plasma furosemide concentration were obtained at 0.5, 1, 1.5, 2, 3, 4, and 6 hours after the agent. There were no significant differences between the two trials in plasma concentrations of furosemide or urinary excretions of the agent. Urine volume and urinary excretions of electrolytes (Na, Cl, K, and Mg) after the furosemide with lisinopril administration were not significantly different from those of placebo at any observation period. These results suggest that the urinary excretions of electrolytes after furosemide administration are not influenced by pretreatment with lisinopril.

The effect of age on diurnal variation in the pharmacokinetics of propranolol in hypertensive subjects

There is diurnal variation in the absorption rate of propranolol in younger subjects. This study was undertaken to examine the effect of age on the chronopharmacokinetics of propranolol. We gave 20 mg of propranolol orally to 13 younger and 11 older hypertensive subjects at 09.00 h (day study) or 21.00 h (night study) in a cross-over design. Plasma concentrations of propranolol and its metabolites, 4-hydroxypropranolol and naphthoxylactic acid, were determined just before and at 0.5, 1, 1.5, 2, 3, 4, 6, 12, and 24 h after dosage. In the younger subjects the absorption rate constant (ka) of propranolol and its maximum plasma concentration (Cmax) were significantly higher and the time to maximum concentration (tmax) was significantly shorter in the day than at night. There were similar time-variant changes in Cmax and tmax for 4-hydroxypropranolol and naphthoxylactic acid. In contrast, there were no time-variant changes in ka, Cmax and tmax of propranolol and its metabolites in the older subjects. These results suggest that propranolol is absorbed more rapidly after morning dosing than after night-time dosing in younger but not in older subjects. Based on these findings, we speculate that the time-variance in the absorption rate or first-pass elimination, or both, of propranolol diminish with age.

Differential expression of neuron-glia cell adhesion molecule (Ng-CAM) on developing axons and growth cones of interneurons in the chick embryo spinal cord: an immunoelectron microscopic study

To elucidate the role of neuron-glia cell adhesion molecule (Ng-CAM) in axonal pathway formation of avian spinal interneurons, we have examined the ultrastructural expression of Ng-CAM in the developing spinal cord, by using a preembedding immunocytochemical method. Ng-CAM immunoreactivity was punctate and was restricted to cell surfaces. In accordance with our previous light microscopic observations (Shiga et al., '90), the earliest developing spinal interneurons were Ng-CAM-positive on their cell bodies, axons, and growth cones. Axons and growth cones that were either fasciculated or in contact with each other strongly expressed Ng-CAM, thus indicating the possible involvement of Ng-CAM in fasciculation of axons and in the contact guidance of growth cones along preexisting axons. By using higher resolution immunoelectron microscopy, the present study has also revealed new information on the subcellular localization of Ng-CAM on developing spinal interneurons, neuroepithelial cells, and floor plate cells. Although Ng-CAM immunoreactivity was prominent on both axons and growth cones, these structures were Ng-CAM-negative when they contacted the basal lamina around the spinal cord. By contrast, Ng-CAM was detectable on the surface of both neuroepithelial cells and floor plate cells only when they made contact with the Ng-CAM-positive axons and growth cones of interneurons. These results suggest that the subcellular distribution of Ng-CAM is regulated differentially, depending on the apposing cell surfaces, and that such differential and developmentally regulated expression may contribute to the elongation, fasciculation, and guidance of spinal axons.

Measurement of redox states of mitochondrial cytochrome aa3 in regions of liver lobule by reflectance microspectroscopy

To evaluate the sublobular distribution of oxygen tension, the redox states of mitochondrial cytochrome aa3 were assessed in local regions of the liver lobule by reflectance microspectroscopy. The reflected light from two focused microspots (20 microns in diam) on the surface of the perfused liver, placed on the stage of microscope, was conducted to the spectrophotometer with two separate light guides, giving the reflectance spectra. The redox state of cytochrome aa3 was calculated from the difference in reflectance between 603 and 630 nm. The degree of cytochrome reduction increased with the stepwise decline of the influent or effluent oxygen concentrations. The local oxygen concentration in periportal region for the half-maximal reduction of cytochrome aa3 was higher than that in pericentral region. In addition, the degree of cytochrome aa3 reduction increased with the distance from the periportal region, reflecting a physiological gradient of oxygen tension along the sinusoidal flow, although with an intersinusoidal heterogeneity within liver lobule.

Chronopharmacokinetic study of a new immunosuppressive agent, FK 506, in mice

Chronopharmacokinetic profiles of a new immunosuppressive agent, FK 506, were examined in mice. FK 506 (1 mg/kg) was given orally at 10 AM (day trial) or 10 PM (night trial) once a day for 7 days. Blood samples for measurement of FK 506 concentration in whole blood were obtained just before and at 1, 2, 3, 4, 6, 8 and 12 hr after the final dosage. The time to maximum concentration was shorter and the maximum concentration was greater in the night trial than in the day trial. These findings suggest that absorption of FK 506 is faster and its blood concentrations is higher in the night trial.

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.

Repeated alcohol intake changes circadian rhythm of ambulatory blood pressure

The blood pressure of 7 clinically healthy volunteering social drinkers was studied while they consumed, with a crossover design for 5 days, either 40 g of alcohol by day or fruit juice, with the two spans on alcohol and juice being separated by a one-week washout. Whereas the rhythm-adjusted mean was not changed, a clear statistically significant increase in the circadian double amplitude was found. The study provides a model for a rapidly achieved circadian amplitude hypertension which may precede an elevation of the overall blood pressure mean in the natural course of the disease.

Chronopharmacology of amlodipine in rats

The present study was undertaken to examine whether plasma concentrations of amlodipine, a calcium antagonist, and its diuretic effects vary with the time of dosage. Pharmacokinetic study; 20 mg/kg of amlodipine was given orally to rats at 10 am (day trial) or 10 pm (night trial), and blood samples were obtained during a 24-hour period. Pharmacodynamic study; two doses (10 and 20 mg/kg) of amlodipine were given orally at 10 am or 10 pm by a cross-over design, and urine was collected for 12 hours after dosage. Rats were maintained under condition of light from 7 am to 7 pm. The following results were obtained; The tmax of amlodipine was shorter and the Cmax was greater in the night trial than in the day trial. Its diuretic effects were greater in the night trial. These results suggest that the pharmacokinetic and pharmacodynamic profiles of amlodipine vary with its time of dosage.

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.