Yoshimasa Matsunaga

Effect of sulfo-N-succinimidyl palmitate on the rat heart: Myocardial long-chain fatty acid uptake and cardiac hypertrophy

Abnormal long-chain fatty acid metabolism has been suggested as having a role in the genesis of certain cardiac diseases, and depressed myocardial long-chain fatty acid uptake has been clinically demonstrated in some patients with hypertrophic cardiomyopathy. However, the site where long-chain fatty acid metabolism is affected in cardiomyopathy remains unclear. Although cardiac hypertrophy is reported to be induced in rats by a fat-free diet, little is known of the consequences of depressed myocardial long-chain fatty acid uptake. Sulfo-N-succinimidyl derivatives of long-chain fatty acids have been shown to irreversibly inhibit long-chain fatty acid transport. To investigate the possible linkage of abnormal long-chain fatty acid uptake with cardiac hypertrophy, myocardial long-chain fatty acid uptake was blocked in rats using a sulfo-N-succinimidyl derivative of palmitate (SSP). SSP was intraperitoneally administered to rats for 12 weeks, and its effects on physiological parameters, and cardiac morphology were studied, SSP treatment (20 mg/kg) caused a 12% increase in heart weight (663.7 +/- 33.6 mg in controls v 741.2 +/- 26.5 mg after SSP treatment) and an 11% increase in the heart weight to body weight ratio (2.46 +/- 0.10 in controls v 2.72 +/- 0.17 after SSP) without any significant change of body weight. No significant differences were observed in blood pressure, heart rate, and serum hormones (insulin and triiodothyronine) between the control and SSP-treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Enzymatic hydrolysis of haloperidol decanoate and its inhibition by proteins

When [14C]haloperidol decanoate, a long-acting neuroleptic and an ester of haloperidol and decanoic acid, was incubated in human whole blood and plasma and in rat plasma and homogenates of rat brain, lung, liver, kidney, pancreas and muscle, no hydrolysis of the ester was seen. Although the decanoate was hydrolyzed by partially purified carboxylesterase, addition of rat plasma or liver homogenate to the enzymic reaction mixture resulted in marked inhibition of hydrolysis, whereas addition of the defatted residues of plasma or liver produced only partial inhibition. The enzymic hydrolysis was inhibited also by beta-lipoprotein and albumin, depending on their concentrations. The assumption that interaction between haloperidol decanoate and protein resulted in inhibition of the hydrolytic reaction mediated by the enzyme was validated by kinetic models and experimental data. The kinetics were apparently competitive. Based on the kinetic analysis, the interaction between the decanoate and albumin or beta-lipoprotein was investigated by measuring their equilibrium constants and extent of protein binding. Haloperidol decanoate appeared to interact with several proteins; this was exemplified by other measures of protein binding, an increasing effect of proteins on the solubility, and the partition ratio of the ester. The interaction between haloperidol decanoate and proteins caused marked stabilization of this ester against enzymatic hydrolysis and, thereby, influenced its metabolism.

Simultaneous determination of plasma and urinary uric acid, xanthine, hypoxanthine, allopurinol, oxipurinol, orotic acid, orotidine and creatinine by high-performance liquid chromatography

Abstract A new high-performance liquid chromatographic procedure is described for the simultaneous determination of plasma and urinary uric acid, xanthine, hypoxanthine, allopurinol, oxipurinol, orotic acid and orotidine whose quantities are varied by allopurinol treatment in man. Creatinine was also measurable. The method was established by high-performance liquid chromatography and gas chromatography—mass spectrometry.

Disposition and metabolism of [14C]loperamide in rats.

SummaryFollowing oral administration of [l4C]loperamide hydrochloride in 1 mg/kg to rats, plasma levels of radioactivity reached maximum at 4 hrs and decreased with a half-life of 4.1 hrs. Radioactivity in 964ir feces accounted for 95% of the dose, with 30% associated with unchanged drug, while that in urine only 3.5%. Radioactivity in 48-hr bile accounted for 42% of the dose associated entirely with metabolites. 3% of the dose was found at the level of the enterohepatic cycles. These findings show that about 70% of the dose was absorbed by intestine, the target tissue of the drug, a portion (30%) of which was excreted back into intestinal cavity after demethylation, while the remaining 40% transferred to liver by which it was extracted mostly, metabolized extensively and excreted largely into bile, as supported by in vitro demethylating activity in gut segments but none in gut contents, and by in situ marked hepatic extraction of the drug. Main metabolic pathways involved are described.

Absorption of intramuscularly administered [14C]haloperidol decanoate in rats

SummaryWhen [14C]haloperidol decanoate, an ester of haloperidol and decanoic acid, was given intramuscularly to rats, levels of total radioactivity and haloperidol decanoate in medial iliac and hypogastric sacral lymph nodes nearest to injection sites were the highest in examined lymph nodes and plasma. These lymph node levels became maximum 16 days after administration and declined gradually with half-life (around 14 days) similar to those of plasma total radioactivity, haloperidol decanote and haloperidol. However, when the labelled ester was given intravenously, plasma total radioactivity disappeared far more rapidly. Much more radioactivity was found in hind limbs whose femoral muscles had been injected than in other body parts, even at late stages after administration. Haloperidol alone was found in the brain after [14C]haloperidol decanoate was given either intramuscularly or intravenously. It was concluded that haloperidol decanoate injected in rat femoral muscle was rate-limitedly distributed in lymph circulation and that the absorbed ester did not penetrate the brain through the blood-brain barrier but formed haloperidol did.

Distribution of [14C]labeled purines in the mouse. A whole body autoradiographic assessment of purine metabolism in mammals.

In order to evaluate circulating purines in mammals systemically, mice received intravenous injections of [‘4C]labeled purines and their incorporation into tissues was assessed by whole-body autoradiography with the aid of metabolic inhibitors, reference purines and pyrimidines and a few biochemical confirmations. The results of this work clearly showed that the incorporation of purines is tissue-specific and possibly related to the functions of the organs. Adenosine was incorporated into tissues of the so-called energetic type, into tissues having high vascularity such as the heart and lung, and into erythrocytes. Nearly all of the incorporation of inosine occurred only after its conversion to hypoxanthine. Hypoxanthine was incorporated not only into the kidney but also into peripheral tissues such as bone marrow, lymph node, thymus, intestinal mucosa and submaxillary gland that rapidly synthesize nucleic acids and have at least a partial requirement for hypoxanthine supplied from other tissues by way of erythrocytes. Xanthine and successive metabolites were not retained by tissues but were rapidly metabolized and excreted. This gross survey of purine uptake from the systemic circulation provides a way of assessing the relative importance of systemic salvage of circulating purines among different tissues in an animal body. The whole-body autoradiographic technique has been shown to furnish systemic information on biochemical processes relating to purine metabolism that occur throughout the animal body. The technique itself offers a wide potential for the study of other systemic biochemical phenomena in vivo.

Regional distribution of 14C-zonisamide in rat brain

Zonisamide (1,2-benzisoxazole-3-methane sulfonamide) is a new antiepileptic drug developed in Japan. This compound was proven to possess a strong inhibitory effect on convulsions of cortical origin, whether induced by electric or chemical stimuli. Regional distribution of 14C-zonisamide was investigated in rat brain using autoradiography. A high uptake of 14C activity was observed in the cerebral cortex and the midbrain. A pair-match analysis of primary motor cortex versus primary sensory cortex revealed a slightly higher uptake in primary motor cortex. In the cerebellum, a higher uptake was observed in the cortex than medulla. Sagittal section analyses revealed that a high uptake of 14C activity was observed in the cerebral cortex and colliculus, and a moderate uptake was seen in the cerebellum, thalamus, hypothalamus, and striatal body, thus suggesting the distribution of 14C-zonisamide is similar to that of flunitrazepam and phenytoin.

Hydrolysis of haloperidol decanoate in vitro by cultured cells

Summary[14C] Haloperidol decanoate was hydrolysed by partially purified carboxylesterase but not in plasma, blood, lymph and lymphatic liquid. These fluids inhibited the enzyme-mediated hydrolysis of the ester. Within the same incubation period as above, the ester was found hydrolysed to various extents in cell cultures of isolated rat liver cells, of human and rat lymphocytes and of established cell lines (BGM cells, WI-38 cells and L6 cells). Thus, the hydrolysis of the ester was demonstratedin vitro with use of viable cell cultures instead of enzyme preparation. From the time course study on the metabolism of haloperidol decanoate in cell cultures, it was concluded that haloperidol decanoate was first concentrated in the cells and hydrolysed to haloperidol. Based on these results, the metabolic sequencesin vivo leading to the formation of active principle haloperidol after intramuscular administration of its decanoate were discussed.

Mode of antitumor action of recombinant human tumor necrosis factor on the sarcoma Meth A transplanted in the mouse.

The mode of antitumor action of rHu-TNF was elucidated in BALB/c mice bearing Meth A fibrosarcoma 7 days after transplantation with respect to time course, dose-response relationships and selectivity of the effects. The maximal cytotoxic effect on tumor cells revealed by inhibition of DNA synthesis and maximal lesional effect on tumor vasculature revealed by change in blood pool-size in the tissue were detected at 30 min and I h after administration of rHu-TNF, respectively. The dose-response relationship between cytotoxic and tumoricidal effects of rHu-TNF was irrespective of administration route. ED50s of these antitumor effects afteri.v. administration of rHu-TNF were about 50 times as high as ED50s afteri.t. administration. ED50 ofi.t. given rHu-TNF for vascular effect was about 20 times as high as that for cytotoxicity while ED50 ofi.v. rHu-TNF for vascular effect was only 2–3 times as high as that for cytotoxicity. The whole body autoradiographies with [125I] HSA giveni.v. to see the blood influx into tumor tissue and [14C]thymidine given i.v. to see DNA synthesis in the whole body after administration of rHu-TNF revealed that the distribution of radioactivity was markedly changed in the tumor alone without any detectable change in other whole body tissues.In conclusion, thein vivo antitumor effect of rHu-TNF giveni.t. ori.v., appears to be exerted through the direct action on Meth A sarcoma rather than indirectly on tumor vasculature. Under present conditions, the effect of rHu-TNF in the whole body tissues seems rather selective on cells and vasculature of the tumor.