Pharmacological study of BRS, a new bicarbonated Ringer's solution, in haemorrhagic shock dogs.

BACKGROUND AND OBJECTIVES: Sodium bicarbonate is the most physiological alkalinizing agent. The effect of a new bicarbonated Ringer's solution (BRS) containing Mg2+, on metabolic acidosis and serum magnesium abnormality were evaluated and compared with those of acetated Ringer's (ARS), lactated Ringer's (LRS) and Ringer's (RS) solutions in an experimental haemorrhagic shock model with dogs. METHODS: Animals were randomly divided into six groups (n = 6 in each group), a sham-operated group, an operated group without infusion, and 4 operated groups with infusion (BRS, ARS, LRS and RS groups). Each RS was intravenously administered at 60 mL kg(-1) h(-1) for 1.5 h. Arterial blood gases, plasma electrolytes and cardiovascular parameters were analysed. RESULTS: BRS significantly improved blood base excess values, which were decreased by blood-letting, faster and more markedly than did LRS and RS (BRS--6.3 +/- 0.5 mEq L(-1); LRS--9.2 +/- 1.1 mEq L(-1); RS--12.4 +/- 1.0 mEq L(-1) at the end of infusion). The alkalinizing effect of BRS tended to be better than that of ARS but not significantly so. The serum Mg2+ concentration was well-maintained by BRS as compared to other RS (BRS 1.5 +/- 0.0 mgdL(-1); ARS 1.2 +/- 0.0mgdL(-1); LRS 1.1 +/- 0.0mgdL(-1); RS 1.3 +/- 0.1 mgdL(-1), at the end of infusion). CONCLUSIONS: These results suggest that BRS is a suitable perioperative solution for metabolic acidosis and serum electrolyte balance among RS tested.

Pharmacological study of BRS, a new bicarbonated Ringer's solution, in partially hepatectomized rabbits.

BACKGROUND AND OBJECTIVE: The effects of bicarbonated Ringer's solution were evaluated and compared with those of acetated Ringer's, lactated Ringer's and Ringer's solutions in partially hepatectomized rabbits. METHOD: Animals were randomly divided into six groups (n = 6 in each group): a sham-operated group, an operated group without infusion, and four operated groups with infusions of each of the four Ringer's solutions. Each Ringer's solution was intravenously administered at 40 mL kg(-1) h(-1) for 1.5 h. Arterial blood gases, plasma magnesium concentrations and cardiovascular parameters were analysed. RESULTS: The partial hepatectomy-induced decrement of base excess was inhibited by bicarbonated Ringer's solution more remarkably than by either lactated or plain solutions (P < 0.01). The alkalinizing effect of bicarbonated Ringer's solution tended to be more marked than that of the acetated solution but not significantly so. Plasma magnesium concentrations were well maintained by bicarbonated solution as compared to the other solutions (P < 0.01). CONCLUSIONS: These results suggest that bicarbonated Ringer's solution is the most suitable perioperative solution for metabolic acidosis and plasma electrolyte balance among the Ringer's solutions tested.

Inhibitory effects of fluvastain and its metabolites on the formation of several reactive oxygen species.

We investigated the inhibitory effects of fluvastain (FV) and its metabolites (M-2, M-3, M-4, M-5, and M-7) on the formation of several reactive oxygen species (ROS), such as singlet oxygen (1O2), superoxide anion (O2-), hydroxy radical (*OH), hypochlorite ion (OCL-), and linoleic acid peroxide (LOO*). Inhibitory effects of pravastatin (PV), simvastatin (SV), probucol (PR) and alpha-tocopherol (TOC) were also tested. The inhibitory effects of 5-hydroxy FV (M-2) and 6-hydroxy FV (M-3) on the formation of 1O2, O2-, *OH, and OCL- were strongest. Scavenging of 1O2 by M-4, M-5, (+)-FV, and (-)-FV was also noted. The inhibitory effects of (+)-FV on the formation of 1O2 were comparable to those of (-)-FV, PV, SV, PR and M-7 had little or no inhibitory effect on the formation of several ROS. In conclusion, FV and its metabolites, particulary M-2 and M-3, have the potential to protect against oxidative stress mediated by several ROS.

[Antioxidative effects of fluvastatin, and its major metabolites [II]].

We investigated the antioxidative effects of fluvastatin (FV or (+/-)-FV), each enantiomer ((+)-FV, (-)-FV) and its major metabolites on lipid peroxidation using rat and human liver microsomes. The extent of NADPH induced microsomal (Ms) lipid peroxidation was determined by thiobarbituric acid (TBA) assay. The antioxidative effect of each compound was shown as the percentage of inhibition on the formation of TBA reactive substance (TBARS) against vehicle control. The antioxidative effects of alpha-tocopherol (Toc), a potent antioxidative vitamin, probucol (PR), a potent antioxidative drug, pravastatin (PV) and simvastatin (SV), HMG-CoA reductase inhibitors, were also tested. The (+/-)-FV inhibit the formation of TBARS by 40 to 70% depending on Ms concentrations. The antioxidative effects of PR and TOC were comparable to those of FV. The inhibitory effects of PV and SV on the formation of TBARS were less potent than (+/-)-FV, PR and TOC. (+)-FV, (-)-FV, and (+/-)-FV inhibited the formation of TBARS by approximately 50% using rat hepatic microsomes. The antioxidative effects of (+)-FV was comparable to that of (-)-FV using human hepatic microsomes. These results indicated that the antioxidative effects of (+)-FV were comparable to those of (-)-FV, although the HMG-CoA reductase inhibitory activity of (+)-FV was 30-fold higher than that of (-)-FV.

[Arteriovenous fistula associated with Staphylococcus aureus sepsis in a patient with Rendu-Osler-Weber syndrome].

A 58-year-old man with a history of cerebral infarction and bleeding due to duodenal ulcer was admitted with fever and arthralgia. Methicillin-sensitive Staphylococcus aureus (MSSA) was isolated from his peripheral blood. Bacteremia with MSSA was diagnosed, and antibiotic therapy was started. However, chest X-ray films and computed tomographic scans disclosed mass shadows in both lungs accompanied by dilated vascular markings. Pulmonary arteriography and magnetic resonance angiography revealed the existence of arteriovenous fistulas in both lungs. Ga scintigraphy disclosed a hot spot in the left lower lobe, consistent with the location of one fistula. This indicated that the fistula might be the focus of MSSA sepsis. Because the patient also had telangiectasia in his gastric mucosa, oral cavity, and nasal cavity, he was given a diagnosis of Rendu-Osler-Weber syndrome.

Cellular uptake of fluvastatin, an inhibitor of HMG-CoA reductase, by rat cultured hepatocytes and human aortic endothelial cells.

AIMS: To clarify the mechanism for cellular uptake of fluvastatin (FV) into rat primary cultured hepatocytes and human aortic endothelial cells (HAEC). METHODS: Rat primary cultured hepatocytes and Endocell-AO as normal human aortic endothelial cells were used. Effects of incubation time, concentration- and temperature-dependency on cellular FV uptake were investigated after incubation with [14C]-FV and its enantiomers, (+)-FV and (-)-FV. Rat primary cultured hepatocytes were washed with either Na+-containing buffer or Na+-free buffer and incubated with metabolic inhibitors or bile acids. Intracellular radioactivity was measured by liquid scintillation counting. The determination of intracellular unchanged FV and its enantiomers was carried out by stereospecific h.p.l.c. RESULTS: In rat cultured hepatocytes, concentration- and temperature-dependent saturable uptake of [14C]-FV was observed (Km=37.6 microm, V max=869 pmol (mg protein)-1 min-1 ), suggesting a specific uptake mechanism. The uptake of each enantiomer also showed a specific uptake mechanism as observed for the racemate with no difference between enantiomers; (+)-FV, Km=38.5 microm, V max=611 pmol (mg protein)-1 min-1, (-)-FV, Km=41.5 microm, V max=646 pmol (mg protein)-1 min-1. In the presence of cholate and taurocholate, the uptake of FV was inhibited by 39-46%. Pravastatin inhibited FV uptake by 29%. In the absence of Na+, the uptake of FV was markedly inhibited 91-96% by bile acid. The uptake of FV into HAEC at 37 degrees C and 4 degrees C increased with the concentration of FV, but no saturable uptake was observed. CONCLUSIONS: FV transport system may be, at least in part, Na+- and ATP-dependent, and may have some features in common with the bile acid transport system and the organic anion transport system. Since saturable uptake was not observed in HAEC, FV appears to be taken up into these cells mainly via nonspecific simple diffusion.

[Antioxidative effects of fluvastatin, and its major metabolites].

Fluvastatin (FV) is a highly potent inhibitor of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase. Recently, its antioxidant effect caused by inhibiting the formation of low density lipoproteins (LDL) in vitro has been reported. In this study, we reported the antioxidant effects of FV and its major metabolites in human (M-2, M-3, M-4, M-5, and M-7) on lipid peroxidation using rat liver microsomes. The extent of NADPH-induced microsomal (Ms) lipid peroxidation was determined by the thiobarbituric acid (TBA) assay. The antioxidant effect of each compound was shown as the percentage of inhibition on the formation of TBA reactive substances (TBARS) against the vehicle control. Probucol (PR), a potent antioxidant drug, was used as a reference control. The concentration of each compound in this experiment was set at 0.1 mM (final conc.). FV inhibited the formation of TBARS by 30 to 60% without depending on the used Ms concentrations (0.025-0.2 mg protein/ml). The antioxidant effects of M-2, M-3, and M-5 were comparable to that of FV at low Ms concentrations. At the highest Ms concentration, however, the antioxidant effects of these metabolites were considerably higher than that of FV. Inhibition of the formation of TBARS by M-4 or M-7 was approximately 30% of the control and independent of the used Ms concentrations. The antioxidant effect of PR was comparable to those of M-2, M-3, and M-5 in this study. Pravastatin (PV), a potent inhibitor of HMG-CoA reductase, reduced the formation of TBARS around 20% at 0.25 or 0.5 mg protein/ml of Ms concentrations. But the value of percentage of inhibition was around 5% at 0.1 or 0.2 mg protein/ml of Ms concentrations. In conclusion, the antioxidant effects of FV, M-2, M-3, and M-5 were found to be comparable to that of PR.

[Pulmonary metastasis of axillary sweat gland carcinoma: a case report].

A case of axillary sweat gland carcinoma which metastasized to both lungs five years after resection of the primary lesion is described. After the resection of right lung metastasis, systemic chemotherapy was performed, but no response was achieved. The patient has no complaints now, but there are new and multiple metastases in both lungs. I propose that the complete remission can be achieved only by resections.

Effect of SDZ PSC 833 ([3'-keto-Bmt1]-[Val2]-cyclosporin) on serum protein binding and distribution to blood cells of doxorubicin, vincristine and etoposide in vitro.

SDZ PSC 833 ([3'-keto-Bmt1]-[Val2]-cyclosporin) is a P-glycoprotein-mediated multidrug resistance modulator currently undergoing clinical trials. SDZ PSC 833 modulates not only antitumor activity but also tissue distribution of doxorubicin in mice. Since protein binding in plasma/serum and distribution to blood cells are important factors affecting the tissue distribution and excretion of drugs, we investigated the effect of SDZ PSC 833 on serum protein binding and distribution to blood cells of doxorubicin, vincristine and etoposide in vitro. Unbound fractions in serum and fractions distributed to blood cells of either [14C]doxorubicin, [3H]vincristine or [3H]etoposide were determined using serum and blood obtained from mice and healthy volunteers. Effects of SDZ PSC 833 at 3 microg/ml, which was an achievable concentration in a clinical trial of SDZ PSC 833, on protein binding and distribution of the drugs to blood cells were negligible in mouse and human blood in vitro. The absence of interaction between PSC 833 and the anticancer drugs in protein binding and distribution to blood cells suggested the existence of other mechanisms. Possible interactions are speculated to be inhibition of P-glycoprotein function contributing to drug excretion and tissue distribution and inhibition of drug metabolism mediated by cytochrome P450 3A.

[Pharmacokinetic investigation of 5-day multiple dose of tropisetron capsule in patients who had received cisplatin and the usefulness of tropisetron capsule in the treatment of nausea and vomiting].

We have investigated the pharmacokinetics of a 5-day multiple oral dose of 5 mg tropisetron capsule in patients with malignant tumour who had received cisplatin single administration. Its anti-emetic effects on acute and delayed emesis and vomiting were also investigated. During the 5 days after this administration, changes in the release and metabolism of serotonin were investigated. The results may be summarized as follows: 1) The pharmacokinetic parameters of tropisetron revealed no significant change in the data between day 1 and day 5. Also, the parameters were almost similar to those observed in healthy adult males (clinical phase I study); Cmax. T1/2 and AUC 0-24 hrs on day 1 were 9.1 +/- 2.1 ng/ml, 12.5 +/- 4.2 hrs, 85.5 +/- 22.7 ng.hr/ml, respectively. The urinary excretion of the parent drug up until 24 hours after administration on day 1 was 3.8% of the dose administered and 2.9% of the total dose after the last administration; no difference in the urinary excretion rate was observed in healthy subjects. It was thus suggested that hydration accompanied by cisplatin administration did not affect the pharmacokinetics of tropisetron. 2) The changes in the amount of urinary excretion of 5-hydroxy-indoleacetic acid (5-HIAA) during 5 days after cisplatin administration were observed; urinary excretion of 5-HIAA increased 2.3 times (1.3-5.4 times) the baseline on the average during 6 to 12 hours on day 1. In 6 out of 10 patients, the increases in urinary excretion of 5-HIAA showed double or more the baseline during 2 to 5 days after cisplatin administration. Serotonin was thus deemed to be related to the development of delayed emesis. 3) The anti-emetic effects of tropisetron on acute and delayed emesis and vomiting were rated as "markedly effective" in 6 out of 11 patients (54.6%) and "effective" in 1 out of 11 patients (9.1%) on day 1; vomiting did not occur in any of these 7 patients. Tropisetron also controlled emesis and vomiting during days 2-5, and was rated as "almost favorable" in 6 out of 11 patients (54.5%). Further, in 4 out of 6 patients, in whom the urinary excretion of 5-HIAA was increased on day 2 onwards, vomiting did not occur during the time when the urinary excretion of 5-HIAA was increasing. On the basis of the above results, tropisetron is deemed to have certain antiemetic effects on delayed vomiting as well. Its 5-HT3 receptor mediated mechanism was similarly seen to inhibit acute nausea and vomiting.

Effect of fluvastatin, an inhibitor of 3-hydroxy-3-methyl glutaryl CoA reductase, on drug-metabolizing enzymes in rats.

Fluvastatin (FV), a new cholesterol-lowering agent, has been studied for its effects on hepatic microsomal drug-metabolizing enzymes in male rats. FV was orally administered in dosages of 1, 5, and 30 mg/kg/day for 7 consecutive days. 3-Hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase activities were markedly decreased at all dose levels. The amount of microsomal protein and the contents of cytochromes P450 and b5 did not change. No induction of aniline hydroxylase, aminopyrine N-demethylase, testosterone hydroxylases (15 alpha-, 7 alpha-, 6 beta-, 16 alpha-, and 16 beta-), and UDP-glucuronosyltransferase were found. On the other hand, 7-ethoxycoumarin o-deethylase activity was slightly increased and lauric acid omega-1-hydroxylase activity tended to be decreased after treatment with FV.

[Anticoagulant effect of a single bolus injection of parnaparin sodium (LHG) on a hemodialysis model in dogs].

Hemodialysis was performed on dogs, following intravenous bolus injections of LHG at dosage levels of 50, 100 and 200 IU/kg and heparin at the levels of 100 and 200 IU/kg. LHG exerted dose-dependent anticoagulant effects and prolonged the hemodialysis time, compared to heparin with similar anti-Xa activity. When LHG was administered, the half-life of plasma anti-Xa activity was longer than that of heparin at similar anti-Xa activity. LHG prolonged the activated partial thromboplastin time (APTT) linearly and dose-dependently. However, the prolongation was much less than that of heparin, and the anticoagulant activity of LHG continued even after the APTT returned to the value before LHG administration. When LHG was administered, whole blood Xa activated coagulation time (XCT) and plasma Xa activated coagulation time (PXCT) were prolonged in a significantly greater degree compared to APTT. Therefore, XCT and PXCT were considered to be appropriate parameters for monitoring LHG. In the groups administered with LHG at 100 and 200 IU/kg, where hemodialysis could be continued for 8 hr, the tissue factor pathway inhibitor (TFPI) activity in the plasma tended to show a sustained increase. These findings suggested the possibility that not only the antithrombin III dependency mechanism but also the TFPI mechanism contributed to a longer LHG hemodialysis duration compared to heparin administration.

Inhibitory effect of the nonpeptide angiotensin II receptor antagonist losartan and its active metabolite, E-3174, on cAMP phosphodiesterase: additional action of the antagonists.

The inhibitory effects of the nonpeptide angiotensin II (AII) receptor antagonist losartan and its active metabolite, E-3174, on bovine brain calcium/calmodulin-dependent 3':5'-cyclic nucleotide phosphodiesterase (cAMP PDE) were investigated. Losartan and E-3174 inhibited cAMP PDE activity competitively with an apparent Ki of 18.7 +/- 2 microM (N = 3) and 70.4 +/- 8 microM (N = 3) with respect to cAMP, respectively. With 1.2 mM cAMP as a substrate, cAMP PDE activities were inhibited by losartan and E-3174 in a concentration-dependent manner. The concentrations of losartan and E-3174 required to obtain 50% inhibition of the enzyme activity (IC50) were estimated to be 38.9 +/- 7 microM (N = 3) and 139.3 +/- 39 microM (N = 3), respectively. These results show that losartan is about four times more potent than E-3174 in inhibiting the enzyme. The Hill coefficient of -1.0 +/- -0.04 (N = 3) for losartan and -1.1 +/- -0.14 (N = 3) for E-3174 was obtained, indicating that one inhibitor binding site is available on cAMP PDE. This study demonstrated that losartan and E-3174 exert additional inhibitory action on cAMP PDE besides AII receptor antagonism.

In vitro biotransformation of finasteride in rat hepatic microsomes. Isolation and characterization of metabolites.

Metabolism of finasteride ([N-(1,1-dimethylethyl)-3-oxo-4-aza-5 alpha-androst-1-ene-17 beta- carboxamide]; MK-906), a new type of specific inhibitor of testosterone 5 alpha-reductase, was investigated using rat hepatic microsomes. The metabolism of finasteride by rat hepatic microsomes was oxygen- and NADPH-dependent, and addition of metyrapone, 7,8-benzoflavone, and cytochrome c to the incubation mixture inhibited the metabolism of finasteride. It is suggested that the metabolic reaction of finasteride was mediated by a mixed function oxidase involving P-450. Four major metabolites were detected in vitro on incubating finasteride with hepatic microsomes of rats treated with phenobarbital (PB-Ms), whereas two major metabolites were found in the incubation mixture with microsomes of untreated rats (UT-Ms). These metabolites were isolated and purified by solvent extraction and semi-preparative HPLC, and identified by MS spectrometry and NMR spectroscopy. The metabolites consisted of omega-hydroxy finasteride (M-1), finasteride-omega-al (M-2), finasteride-omega-oic acid (M-3), and 6 alpha-OH finasteride (M-4). M-1 and M-4 are the major metabolites in UT-Ms, and M-1 and M-3 in PB-Ms. These studies revealed that hydroxylation of the t-butyl group and ring hydroxylation at the 6-position were key steps in the metabolism of finasteride in the rat hepatic microsomes. Further, the major metabolite M-4 was hydroxylated at the 6 alpha-position, but not at the 6 beta-position of the drug. This finding suggests the existence of a novel enzyme that catalyzes the 6 alpha-hydroxylation of the 4-azasteroid.

Mechanism of gastroprokinetic effect of EM523, an erythromycin derivative, in dogs.

BACKGROUND: The pharmacological properties of EM523, a nonpeptide motilin agonist, have not been well characterized. METHODS: The prokinetic effect of EM523 on motor-stimulating activity in the stomach, duodenum, and jejunum in seventeen conscious dogs was studied using force transducers implanted long term. EM523 (0.3-10.0 micrograms/kg) and receptor antagonists were injected intravenously during the interdigestive state. RESULTS: EM523 induced phase III-like contractions in a dose-dependent manner, and the contractions were inhibited dose dependently by pretreatment with cholinergic and 5-HT3 receptor antagonists and dopamine but not by adrenoceptor and opiate antagonists or methysergide. The plasma immunoreactive motilin level was increased after EM523 to 60% of the mean maximum value during the spontaneous phase III contractions. Pretreatment with anti-canine motilin serum inhibited EM523-induced contractions by 19.2% in the motor index, but the contractile pattern was not affected. CONCLUSIONS: EM-523-induced phase III-like contractions are brought about through the cholinergic neural pathway and 5-HT3 receptors, and endogenous motilin release is partially involved.

Pharmacokinetics and biochemical efficacy after single and multiple oral administration of losartan, an orally active nonpeptide angiotensin II receptor antagonist, in humans.

1. The pharmacokinetics and biochemical efficacy of losartan, an orally active nonpeptide angiotensin II (AII) receptor antagonist, were evaluated in healthy male volunteers after single and multiple oral administration. 2. Plasma and urinary concentrations of losartan and its active metabolite, E-3174, were determined by a specific high performance liquid chromatographic (h.p.l.c.) method. 3. Plasma concentrations of losartan were proportional to dose over the range of 25 to 200 mg and the terminal half-lives (t1/2,z) ranged from 1.5 to 2.5 h. The mean values of Cmax and AUC0-infinity increased in a dose-dependent manner. 4. Plasma concentrations of E-3174 were higher than those of losartan at all dose levels. The values of Cmax and AUC0-infinity for E-3174 were approximately 2 and 5-8 times higher than those for losartan, respectively. Also the value of t1/2,z was 2 times longer than that of losartan. 5. After multiple dosing for 7 days, the pharmacokinetics of losartan and E-3174 each did not change significantly between day 1 and day 7. 6. Plasma renin activity (PRA) and plasma concentrations of AII increased markedly at all dose levels. Plasma aldosterone levels were slightly reduced, but a similar decrease was also observed with placebo. 7. No clinically significant adverse reaction was observed in any of the volunteers during either study. Blood counts, routine laboratory tests, urine analyses, and electrocardiograms were also not modified by losartan. 8. Losartan appears to be a potent orally active angiotensin II antagonist with a relatively long duration of action.

Pituitary adenylate cyclase activating polypeptide stimulates gallbladder motility in conscious dogs.

We investigated whether pituitary adenylate cyclase activating polypeptide (PA-CAP27 and PACAP38) had any effect on gallbladder motility in conscious dogs, in which force transducers were chronically implanted in the gastric antrum, duodenum and gallbladder. PACAP27 and PACAP38 were administered intravenously during the digestive and interdigestive states at doses of 30, 100 and 300 pmol/kg. By way of comparison, cholecystokinin octapeptide (CCK-OP) was administrated at doses of 3, 9 and 27 pmol/kg. As a result, each peptide evoked transient and tonic contractions both in the digestive and interdigestive states, and the effect on the motor index was dose dependent. PACAP27 and PACAP38 were 0.11 +/- 0.03 and 0.04 +/- 0.01 as potent as CCK-OP in the digestive state, and 0.18 +/- 0.04 and 0.02 +/- 0.01 in the interdigestive state, respectively, on a molar basis. Although PACAP27 and PACAP38 belong to the vasoactive intestinal polypeptide (VIP) family, intravenous administration of 300 pmol/kg of VIP had no effect on interdigestive gallbladder motility, but on the other hand inhibited gallbladder motility in the digestive state. The contractile effects of PACAP27 and PACAP38 were almost completely abolished by pretreatment with atropine or hexamethonium, but not with L364718. An in vitro study using canine gallbladder strips showed that PACAP27 and PACAP38 had no effect on spontaneous gallbladder motor activity evoked by electric field stimulation, CCK-OP or acetylcholine. It was concluded that PACAP27 and PACAP38 stimulate gallbladder motility in conscious dogs through a preganglionic cholinergic mechanism.

Endogenous CCK is not involved in the regulation of interdigestive gastrointestinal and gallbladder motility in conscious dogs.

In this study, we assessed whether endogenous CCK is involved in the regulation of interdigestive gastrointestinal and gallbladder motility in conscious dogs with force transducers chronically implanted in the gastric antrum, duodenum, jejunum and gallbladder. L364718 at a dose of 1.0 mg/kg was used as a specific and potent CCK receptor blocker, and its effect on spontaneous interdigestive motility and plasma motilin release were examined. Additionally, the contractile activity of exogenous synthetic canine motilin (20-100 ng/kg) with or without pretreatment with L364718 at a dose of 1.0 mg/kg was assessed. Whether the blocking effect of L364718 on CCK receptors was sufficient or not was verified by giving CCK-OP at a bolus dose of 10 ng/kg. As a result, cyclic changes in interdigestive motor activity and the plasma motilin concentration were not affected by pretreatment with L364718. L364718 also did not affect motilin-induced interdigestive contractile activity in the gastrointestinal tract and gallbladder. On the other hand, the effect of CCK-OP was completely abolished by pretreatment with L364718. It is concluded that endogenous CCK is not involved in the regulation of spontaneous and motilin-induced interdigestive contractions in the canine gastrointestinal tract and gallbladder.

Study on neutralization of low molecular weight heparin (LHG) by protamine sulfate and its neutralization characteristics.

The neutralizing effects of protamine sulfate (PS) on anticoagulant activities of low molecular weight heparin (LHG) and conventional sodium heparin (Heparin) were investigated. The in vitro anti-factor Xa and APTT-prolonging activities of Heparin were almost completely neutralized by PS, whereas the activities of LHG remained partially intact in the presence of PS. Crossed immunoelectrophoresis of antithrombin III (AT III) and affinity chromatography of LHG- and Heparin-cellulose showed that AT III was substantially less dissociated from its binding to LHG than to Heparin in the presence of PS. As in vitro, the in vivo anticoagulant activities of Heparin administered i.v. to rabbits were almost completely neutralized by PS, while the anti-factor Xa and APTT-prolonging activities of LHG remained partially intact in the presence of PS. The thrombin time-prolonging activity of LHG, however, was completely inhibited by PS. Since the bleeding effect of Heparin or LHG is considered mainly due to its anti-thrombin activity, PS may be used as an agent to neutralize LHG, as in the case of Heparin, when bleeding happens to occur during LHG treatment.

Sex difference in metabolism of simvastatin by rat hepatic microsomes.

Metabolism of simvastatin (SV), a new cholesterol-lowering agent, by hepatic microsomes from male and female rats was investigated. After incubation of [14C]-SV with hepatic microsomes, radioactive metabolites were detected by HPLC. The main metabolite was 3' alpha-hydroxy-SV in male rats and the hydroxy open acid form of SV (SVA) in females. The 3"-hydroxy-SV and 3',3"-dihydroxy-SV which were observed in male rats were hardly detected in females. Specific activity for the metabolism of SV in male rats (3.97 nmol/mg protein/min) was about 9-times higher than that in females. Metabolic activity of hepatic microsomes in male rats was essentially unchanged with increase in age, whereas that in females decreased age-dependently and was very low or negligible after 7 weeks of age. Formation of 3"-hydroxy-SV and 3',3"-dihydroxy-SV in male rats was markedly increased with age, and that in females was negligible at all ages examined.