Relationship between the brain natriuretic peptide (BNP) level and remission of diabetic nephropathy with microalbuminuria: a 3-year follow-up study.

The aim of the study was to examine the relationship between the brain natriuretic peptide (BNP) level and progression or remission of diabetic nephropathy with microalbuminuria for 3 years. The subjects were 100 Japanese type 2 diabetes mellitus outpatients with microalbuminuria. Associations between metabolic parameters at baseline [HbA1c, systolic blood pressure (SBP), urine albumin-creatinine ratio (ACR), estimated glomerular filtration rate (eGFR), and BNP] and the progression or remission of diabetic nephropathy were examined for 3 years. A total of 83 patients were examined at the end of the 3-year period, including 17 with remission to normoalbuminuria, 47 with continuing microalbuminuria, and 19 with progression to macroalbuminuria. HbA1c, ACR, and BNP differed significantly among the 3 groups (p=0.024, p<0.001, p=0.002, respectively). Among baseline factors, HbA1c and BNP were significant predictors of the percentage increase in ACR for 3 years in multiple linear regression analysis (ß=0.259, p=0.02; ß=0.299, p=0.007, respectively). In multivariate logistic regression analysis, HbA1c and ACR were independently associated with progression of diabetic nephropathy (p=0.008, p=0.023, respectively), and ACR and BNP were independently associated with remission of diabetic nephropathy (p=0.029, p=0.012, respectively). ROC curve analysis gave a cutoff value for BNP of 14.9 pg/ml for prediction of remission of diabetic nephropathy (p=0.016). The BNP level has a relationship with diabetic nephropathy and a low BNP level predicts remission of diabetic nephropathy. Therefore, monitoring of BNP can play an important role in management of diabetic nephropathy.

Tofogliflozin, a sodium/glucose cotransporter 2 inhibitor, attenuates body weight gain and fat accumulation in diabetic and obese animal models.

OBJECTIVE: Tofogliflozin, a highly selective inhibitor of sodium/glucose cotransporter 2 (SGLT2), induces urinary glucose excretion (UGE), improves hyperglycemia and reduces body weight in patients with Type 2 diabetes (T2D). The mechanisms of tofogliflozin on body weight reduction were investigated in detail with obese and diabetic animal models. METHODS: Diet-induced obese (DIO) rats and KKAy mice (a mouse model of diabetes with obesity) were fed diets containing tofogliflozin. Body weight, body composition, biochemical parameters and metabolic parameters were evaluated. RESULTS: In DIO rats tofogliflozin was administered for 9 weeks, UGE was induced and body weight gain was attenuated. Body fat mass decreased without significant change in bone mass or lean body mass. Food consumption (FC) increased without change in energy expenditure, and deduced total calorie balance (deduced total calorie balance=FC-UGE-energy expenditure) decreased. Respiratory quotient (RQ) and plasma triglyceride (TG) level decreased, and plasma total ketone body (TKB) level increased. Moreover, plasma leptin level, adipocyte cell size and proportion of CD68-positive cells in mesenteric adipose tissue decreased. In KKAy mice, tofogliflozin was administered for 3 or 5 weeks, plasma glucose level and body weight gain decreased together with a reduction in liver weight and TG content without a reduction in body water content. Combination therapy with tofogliflozin and pioglitazone suppressed pioglitazone-induced body weight gain and reduced glycated hemoglobin level more effectively than monotherapy with either pioglitazone or tofogliflozin alone. CONCLUSION: Body weight reduction with tofogliflozin is mainly due to calorie loss with increased UGE. In addition, tofogliflozin also induces a metabolic shift from carbohydrate oxidation to fatty acid oxidation, which may lead to prevention of fat accumulation and inflammation in adipose tissue and liver. Tofogliflozin may have the potential to prevent obesity, hepatic steatosis and improve insulin resistance as well as hyperglycemia.

Effect of SGLT2 inhibitors in a murine model of urinary tract infection with Candida albicans.

AIMS: Urinary tract infection (UTI) is a common clinical problem in diabetic patients; however, the relationship between UTI and glucosuria remains uncertain. To investigate the relationship, we examined the effect of glucosuria induced by sodium glucose cotransporter 2 (SGLT2) inhibitors on the progression of UTI in mice. METHODS: From 1 day before transurethral inoculation with Candida albicans, female mice were treated orally once a day with an SGLT2 inhibitor in different treatment regimens: (i) dapagliflozin at 10 mg/kg for 2, 3 or 7 days, (ii) dapagliflozin at 0.1, 1 or 10 mg/kg for 3 days and (iii) dapagliflozin, canagliflozin or tofogliflozin at 10 mg/kg for 3 days. To evaluate the ascending UTI, the kidneys were removed 6 days after the inoculation, and the number of viable C. albicans cells in kidney was measured as colony-forming units (CFU). RESULTS: In mice treated with dapagliflozin, the number of C. albicans CFU in kidney increased in accordance with both treatment duration and dose. The number of CFU significantly increased when mice were treated with 10 mg/kg dapagliflozin or canagliflozin but not tofogliflozin. With dapagliflozin and canagliflozin, urine glucose concentration (UGC) significantly increased up to 24 h after drug administration; with tofogliflozin, UGC significantly increased only up to 12 h after drug administration. CONCLUSIONS: Our data indicate that increased susceptibility to UTI is associated with a persistent increase in UGC.

Tofogliflozin, a novel sodium-glucose co-transporter 2 inhibitor, improves renal and pancreatic function in db/db mice.

BACKGROUND AND PURPOSE: Although inhibition of renal sodium-glucose co-transporter 2 (SGLT2) has a stable glucose-lowering effect in patients with type 2 diabetes, the effect of SGLT2 inhibition on renal dysfunction in type 2 diabetes remains to be determined. To evaluate the renoprotective effect of SGLT2 inhibition more precisely, we compared the effects of tofogliflozin (a specific SGLT2 inhibitor) with those of losartan (an angiotensin II receptor antagonist) on renal function and beta-cell function in db/db mice. EXPERIMENTAL APPROACH: The effects of 8-week tofogliflozin or losartan treatment on renal and beta-cell function were investigated in db/db mice by quantitative image analysis of glomerular size, mesangial matrix expansion and islet beta-cell mass. Blood glucose, glycated Hb and insulin levels, along with urinary albumin and creatinine were measured KEY RESULTS: Tofogliflozin suppressed plasma glucose and glycated Hb and preserved pancreatic beta-cell mass and plasma insulin levels. No improvement of glycaemic conditions or insulin level was observed with losartan treatment. Although the urinary albumin/creatinine ratio of untreated db/db mice gradually increased from baseline, tofogliflozin or losartan treatment prevented this increase (by 50-70%). Tofogliflozin, but not losartan, attenuated glomerular hypertrophy. Neither tofogliflozin nor losartan altered matrix expansion. CONCLUSIONS AND IMPLICATIONS: Long-term inhibition of renal SGLT2 by tofogliflozin not only preserved pancreatic beta-cell function, but also prevented kidney dysfunction in a mouse model of type 2 diabetes. These findings suggest that long-term use of tofogliflozin in patients with type 2 diabetes may prevent progression of diabetic nephropathy.

Correlation between imatinib pharmacokinetics and clinical response in Japanese patients with chronic-phase chronic myeloid leukemia.

Despite the outstanding results generally obtained with imatinib mesylate (IM) in the treatment of chronic myeloid leukemia (CML), some patients show a poor molecular response. To evaluate the relationship between steady-state trough plasma IM concentration (IM-C(min)) and clinical response in CML patients, we integrated data from six independent Japanese studies. Among 254 CML patients, the mean IM-C(min) was 1,010.5 ng/ml. Importantly, IM-C(min) was significantly higher in patients who achieved a major molecular response (MMR) than in those who did not (P = 0.002). Multivariate analysis showed that an MMR was associated with both age (odds ratio (OR) = 0.97 (0.958-0.995); P = 0.0153) and with IM-C(min) (OR = 1.0008 (1.0003-1.0015); P = 0.0044). Given that patients with IM-C(min) values >1,002 ng/ml had a higher probability of achieving an MMR in our large cohort (P = 0.0120), the data suggest that monitoring of IM levels in plasma may improve the efficacy of IM therapy for CML patients.

Absence of ubiquitinated inclusions in hypocretin neurons of patients with narcolepsy.

OBJECTIVES: The cause of hypocretin cell loss in human narcolepsy-cataplexy is unknown but has been suggested to be neurodegenerative in nature. To test this hypothesis, we evaluated the remaining hypocretin cells in human narcolepsy brains for the presence of aggregated protein inclusions, gliosis, and inflammation. METHODS: Brains were examined by routine histologic methods for potential comorbid neurodegenerative diseases and through immunohistochemical screening for protein inclusions in the hypothalamus. Hypothalamic sections of 4 subjects with narcolepsy and 5 nonneurologic controls were examined immunohistochemically with antibodies against ubiquitin (a marker of aggregated protein), allograft inflammatory factor 1 (AIF1, a microglial activation marker), glial fibrillary acidic protein (GFAP, a reactive astrocytic marker), and hypocretin. Hypothalami of subjects with narcolepsy were additionally examined for the presence of known components of protein aggregates (tau, alpha-synuclein, amyloid beta, and TDP-43). RESULTS: Hypocretin cells were markedly decreased in all 4 subjects with narcolepsy. Ubiquitinated inclusions were not observed in the total of 96 remaining hypocretin cells in these subjects. Further, we noted that even in patients with dementia neuropathology, the lateral hypothalamic hypocretin area was spared from ubiquitinated inclusions. AIF1 and GFAP staining in the perifornical area was unremarkable. CONCLUSIONS: Our findings suggest that hypocretin cell loss does not involve ubiquitinated inclusions, the hallmark of most neurodegenerative diseases. The lack of increased markers of inflammation also argues against a progressive and continuous neurodegenerative process.

Effects of CP-060S, a novel cardioprotective drug, in the methacholine-induced ECG change model in rats.

We compared the antianginal effect of CP-060S, a novel cardioprotective drug with Na+ and Ca2+ overload-preventing activity as well as Ca2+ channel antagonistic activity, with that of diltiazem, in an experimental model of vasospastic angina induced by methacholine in anaesthetized rats. Intra-aortic injection of methacholine at the coronary ostium provoked the ST-segment elevation of the electrocardiogram (ECG), indicating myocardial ischemia. CP-060S (3, 5 and 10 mg/kg, i.d.) significantly and dose-dependently suppressed the methacholine-induced ST-elevation, with the duration of action being at least 3 h at the highest dose. In addition, CP-060S at 3 mg/kg could inhibit the ST-elevation without producing significant changes in blood pressure, heart rate or rate-pressure product (RPP). In contrast, diltiazem (10 and 30 mg/kg, i.d.) significantly decreased the RPP, a significant suppression of the ST-elevation could only be achieved at the highest dose and its duration of action was about 2 h. Similar results were obtained with i.v. administration of the drugs, i.e. CP-060S given i.v. could inhibit the ST-elevation with less haemodynamic changes than diltiazem. In conclusion, CP-060S exerted a more potent and sustained protection against myocardial ischemia evoked by methacholine than diltiazem. The characteristics of the effects of CP-060S observed here suggest that this drug may be a desirable drug for the treatment of vasospastic angina.

Coronary artery disease as a definitive risk factor of short-term outcome after starting hemodialysis in diabetic renal failure patients.

Cardiovascular disease is a major cause of morbidity and mortality in patients with diabetes who are receiving dialysis. It is known that cardiac mortality is high in the first year of hemodialysis (HD). The purpose of this study was to clarify the prevalence of coronary artery disease (CAD) in patients with diabetes at the initiation of HD, and to investigate the relationship between short-term outcomes after starting hemodialysis and CAD. We performed coronary angiography (CAG), whether or not patient had angina, within one month of initiation of maintenance HD in 17 of 34 consecutive unselected diabetic patients. We studied the two-year survival rate of those with CAD. Eleven patients (65%) were classified CAD-positive. Nine (82%) of these 11 had multivessel disease. Clinical and hematologic factors did not differ significantly between the groups with and without CAD. During the two-year follow-up period, 28 (82%) of 34 patients survived. In patients with CAD the two-year survival rate was 60%. None of the patients without CAD died within 2 years after starting HD. These results suggest that the presence of CAD at the initiation of HD may play a critical role in short-term outcomes after starting HD. We believe that an evaluation of CAD should be performed at the initiation of HD.

[Treatment of 522 patients with sudden deafness performed oxygenation at high pressure].

INTRODUCTION: Oxygenation at high pressure (OHP) is thought to be useful, even though regional blood flow is decreased, because increasing dissolved oxygen prevents the death of nerve tissue. In this report, we retrospectively investigated the effect of OHP on sudden deafness. OBJECT AND METHOD: We reviewed 522 patients treated with OHP at Kagawa Rosai Hospital over a ten-year period (January 1989 to December 1998). We discussed some prognostic factors: comparison between cases which had been treated with OHP previously and those which had not, number of days between onset and beginning of the treatment which included OHP, age, initial averaged five-frequency hearing level, vertigo, tinnitus, complications of OHP, cases of relapse and the time of the onset, which is about season, month and week. OHP was administered at a pressure of 2.5 atmospheres for 80 minutes a day from 10 to 15 times. All patients also received a course of intravenous administration of steroid, vitamin B12, Prostaglandin E1, ATP, and low-molecular dextran. RESULTS: Overall, complete recovery occurred in 19.7% of the patients, definite improvement in 34.9% (complete recovery included), and slight improvement in 58.1% (definite improvement included). Most of the patients (78.0%) were referred by other hospitals, because our hospital was the only one in the Sikoku area which had a big equipment of OHP. All 161 patients had already been treated in other hospitals over 8 days, but they had shown little improvement after the initial therapy. Of this group, complete recovery after the second course of treatment occurred in 13.0% of the patients, definite improvement in 19.3%, and slight improvement in 39.1%. OHP was thus effective for about 40% of patients who had been unresponsive to the initial therapy. Delay in treatment usually produces poor hearing recovery. There was a significant difference between those patients treated within 14 days and those treated 15 days or more after onset. The improvement rate also decreased with age. The prognosis of patients with vertigo was worse than those without vertigo. Tinnitus had no influence on the prognosis. There were no severe complications during the course of OHP, but otitis media with effusion occurred in 90 patients, and paracentesis was performed for 53 patients. CONCLUSION: The treatment of sudden deafness with OHP has been discussed in this report. Important prognostic factors were time between onset and beginning of the treatment which included OHP, age, vertigo, and the initial averaged five-frequency hearing level. We conclude that OHP should be performed within 14 days from onset, and that OHP was able to achieve hearing improvement in many cases unresponsive to the initial therapy if it was performed very early.

Human papillomavirus as a risk factor for head and neck cancers--a case-control study.

A retrospective, case-control study was conducted to examine the relationship between the presence of human papillomavirus types 16 and 18 (HPV16/18) DNA and the risk of head and neck cancers. Twelve out of 74 (16.2%) head and neck cancers contained HPV16/18 DNA, while 3 out of 70 (4.2%) non-cancer controls showed HPV16/18 positivity by polymerase chain reaction. The presence of HPV16/18 DNA was associated with an increased risk of head and neck cancer formation, showing an odds ratio of 4.32, with a 95% confidence interval of 1.26-14.78. Although its epidemiological impact might be smaller than that of other factors like cigarette smoking, the presence of HPV16/18 DNA in the aerodigestive tract is suggested to be a risk factor for human head and neck cancers.

Structure-specific inhibition of cholesteryl ester transfer protein by azaphilones.

The effect of thirteen different fungal azaphilones, which have a common 6-iso-chromane-like ring, was tested on cholesteryl ester transfer protein (CETP) activity in vitro. Chaetoviridin B showed the most potent inhibitory activity with an IC50 value of < 6.2 microM, followed by sclerotiorin with an IC50 value of 19.4 microM. Rotiorin, chaetoviridin A and rubrorotiorin had moderate inhibitory activity (IC50 ; 30 approximately 40 microM), but others showed very weak or no inhibitory activity. The relationship between the structures and their inhibitory activity indicated that the presence of an electrophilic ketone(s) and/or enone(s) at both C-6 and C-8 positions in the isochromane-like ring is essential for eliciting CETP inhibitory activity. The transfer activity of both CE and TG was inhibited by sclerotiorin to approximately the same extent (IC50: 14.4 and 10.3 microM, respectively). A model of the reaction suggested that sclerotiorin reacts with a primary amine of amino acids such as lysine in the protein to form a covalent bond.

The anti-ischemic effects of CP-060S during pacing-induced ischemia in anesthetized dogs.

CP-060 S, (-)-( S)-2-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-3-[3-[N-methyl-N-[2-(3 ,4-methylenedioxyphenoxy)ethyl]-amino]propyl]-1,3-thiazolidin++ +-4-one hydrogen fumarate, is a novel cardioprotective drug which prevents Na+-, Ca2+-overload and has Ca2+ channel blocking activity. We compared the anti-ischemic effects of CP-060S with those of diltiazem, a Ca2+ channel blocker, and R56865, N-[1-[4-(4-fluorophenoxy)butyl]-4-piperidinyl]-N-methyl-2-benzothiazo lamine, a Na+-, Ca2+-overload inhibitor, in a canine pacing-induced ischemia model. CP-060S 100 microg kg(-1) significantly suppressed the pacing-induced ischemic epicardial ST-segment elevation by maximally 75%, while diltiazem 100 microg kg(-1) suppressed it by maximally 35%. R56865 100 microg kg(-1) significantly suppressed the ST-segment elevation by maximally 30%. In addition, diltiazem 100 microg kg(-1) caused synergistic suppression of ST-segment elevation by 70% when administered simultaneously with R56865 100 microg kg(-1). These results suggest that a Na+-, Ca2+-overload preventive action and a Ca2+ channel blocking action independently contribute to the suppression of the ST-segment elevation. Therefore, CP-060S may suppress pacing-induced ST-segment elevation by a dual action by preventing Na+-, Ca2+-overload and the Ca2+ channel blockade.

[Long-term outcome of coronary events in hemodialysis patients younger and older than 65 years of age].

BACKGROUND AND AIM: It has been reported that a coronary event is the leading cause of mortality in HD patients. The aim of this study was to examine and compare prospectively the effect of aging in relation to the in-hospital and the long-term outcome in HD patients with or without revascularization therapy who had experienced a coronary event. STUDY PATIENTS AND METHODS: Seventy consecutive HD patients with coronary events (9 AMI, 48 AP, and 13 CHF) were registered in this study and 69 patients underwent CAG. Patients were classified into elderly (> or = 65, n = 33) and younger (< 65, n = 37) groups based on their ages at the time of the events. Forty-six patients (21 vs 25) underwent initial coronary revascularization therapy. We followed 70 HD patients with coronary events for a mean period of 31 +/- 21 months (range: 1 day to 77 months). RESULTS: A level of 64% of the elderly group and 41% of the younger group experienced coronary events within the first year of HD. The diseased vessels (2.2 vs 1.9 per patient) and stenotic lesions (2.8 vs 2.5 pre patients) were not significantly different between the two groups. The 70-month survival rate was significantly lower (21% vs 65%, p = 0.0423) in the elderly group than in the younger group. The complicated rate of stroke after a major event was significantly higher (14 vs 4, p = 0.0025) in the elderly group than in the younger group. Moreover 21 elderly patients (11 cardiac death, 5 stroke, 4 cancer) and 9 younger patients (8 cardiac death, 1 stroke) died during the 70-month follow-up period. CONCLUSIONS: Coronary events were most frequent in the first year of HD. Long-term survival rate was significantly lower in elderly patients than in younger patients. Cardiac death was the most common cause of death in both groups regardless of performing coronary revascularization. Death due to stroke and cancer was also more common in elderly patients.

[Portal hypertensive gastropathy and colopathy].

Gastrointestinal bleeding in patients with portal hypertension is usually secondary to esophageal varices, but massive bleeding from gastric mucosal lesions and colonic mucosal lesions including colorectal varices, have been variably described. These lesions are called portal hypertensive gastropathy and colopathy. The incidence and profile of portal hypertensive gastropathy (PHG) has been frequently reported during the last decade, and many studies showed that development of PHG is influenced by coexisting esophageal varices, absence of major portal systemic shunts, severity of liver disease and sclerotherapy and is directly correlated with portal venous pressure. Although hyperdynamic congestion seems to be the underlying mechanisms for the development of PHG, results of gastric mucosal blood flow in patients with PHG is controversial. The treatment can be currently recommended to prevent bleeding, is oral administration of propranolol which decreased portal venous pressure. The clinical feature and profile of portal hypertensive colopathy is classified two groups, which are named colorectal varices and colonic mucosal lesions including vascular spider, dilated fine branching vessels. Although colorectal varices are usually seen at rectum and sigmoid colon, colonic mucosal lesions are seen all part of colon. Significant relationship between colorectal varices and liver disease has been reported and colorectal varices is highly appeared in patients with extrahepatic portal obstruction. Such patients are revealed arteriovenous communications at angiogram. In general, colonic resection or transanal ligation should be the first option for treatment of bleeding colonic varices and colonic mucosal lesions. Transendoscopic sclerotherapy may be an alternate choice.

Lectin-gradient gel affinity electrophoresis of glycoproteins.

Lectin-gradient agarose gel affinity electrophoresis was developed for identification of glycoforms of glycoproteins in lectin affinity electrophoresis. Gradation of lectin was done by stacking agarose gel blocks with increasing concentrations of lectin (discontinuous system) and by keeping the plate in a moist chamber at 4 degrees C overnight (continuous system) before electrophoresis. On the visualization of separated glycoform lines, the antibody-affinity blotting was superior for low concentrations of alpha-fetoprotein. Fluoresceine isothiocyanate (FITC) labeling of whole serum proteins, enzyme activity staining for alkaline phosphatase, and prestaining for lipoproteins were also applicable for visualization of proteins at higher concentrations. The conventional Western blotting can not be recommended because of the competition between lectin and glycoproteins in binding to nitrocellulose membrane. Lectin-gradient affinity electrophoresis also had a wide application for optimization of the condition of lectin affinity electrophoresis.

Osteoma with cholesteatoma in the external auditory canal.

We report an unusual case of a 13-year-old girl with a benign osteoma associated with a cholesteatoma in the external auditory canal and serous otitis media. The osteoma was located in the antero-inferior wall of the right external auditory canal. A cholesteatoma was present between the osteoma and the tympanic membrane. Computed tomography revealed a soft tissue density within the external auditory canal and in the middle ear cleft. The shadow in the middle ear cleft was considered to represent the serous otitis media. Surgical removal of the osteoma and cholesteatoma proved successful, and no recurrences or complications have occurred in the first year postoperatively.

Long-term prognosis of non-shunt operation for idiopathic portal hypertension.

This report presents 46 Japanese patients with idiopathic portal hypertension (IPH) in whom non-shunt operation was performed for the management of esophageal varices. Non-shunt operation included transthoracic esophageal transection (Sugiura's procedure) in 37 patients, transabdominal esophageal transection (TAET) in 3 patients, and Hassab's procedure in 6 patients. Rates of postoperative variceal eradication were: 78.4% by Sugiura's procedure; 100% by TAET; and 50% by Hassab's procedure. The cumulative rates for recurrent varices and recurrent bleeding were 3.9%, and 5.1%, respectively, at 5 years, and 8.9% and 9.8% at both 10 and 15 years. Only 3 patients required additional endoscopic injection sclerotherapy to treat recurrent varices. Although 3 patients developed upper gastrointestinal bleeding, the source of hemorrhage was esophageal varices in 1, and portal hypertensive gastropathy in 2; none of the patients died from bleeding. Actuarial survival for all patients was 87.5% at 5 years, 77.9% at 10 years, and 58.8% at 15 years. There were no deaths within the first 30 days after surgery. These results show that non-shunt operation is useful in preventing bleeding from esophageal varices in patients with IPH.

The protective effects of CP-060S on ischaemia- and reperfusion- induced arrhythmias in anaesthetized rats.

1. CP-060S is a novel sodium and calcium overload inhibitor, and is also characterized as a calcium channel blocker. As these activities have each been shown independently to ameliorate ischaemia damage in the myocardium, the combination may synergistically exert cardioprotection. In this study, therefore, the protective effect of CP-060S against ischaemia- and reperfusion-induced arrhythmia was evaluated in anesthetized rats. 2. Rats were anaesthetized with pentobarbitone, and the left anterior descending coronary artery was occluded for either 5 min with subsequent reperfusion (a reperfusion-induced arrhythmia model) or 30 min without (an ischaemia-induced arrhythmia model). All drugs were intravenously administered 1 min before the onset of occlusion. 3. In the reperfusion-induced arrhythmia model, the animals in the vehicle-treated group exhibited ventricular tachycardia (VT) in 100%, ventricular fibrillation (VF) in 89%, and death caused by sustained VF in 56%. CP-060S (30-300 microg kg(-1)) dose-dependently suppressed the incidences of arrhythmias. Significant decreases occurred at 100 microg kg(-1) in VF (incidence: 42%) and mortality (8%), and at 300 microg kg(-1) in VT (50%), VF (33%) and mortality (8%). This protective effect of CP-060S was 10 times more potent than that of a pure calcium channel blocker, diltiazem (30-1000 microg kg(-1)) we tested, in terms of effective dose ranges. As both drugs decreased myocardial oxygen consumption estimated by rate-pressure product to a similar extent, the calcium channel blocking activity of CP-060S would not seem to be sufficient to explain its potency. 4. In the same model, co-administration of ineffective doses of diltiazem (300 microg kg(-1)) and a sodium and calcium overload inhibitor, R56865 (100 microg kg(-1)), produced significant suppression of VT (incidence: 62%), VF (46%) and mortality (8%). By contrast, co-administration of R56865 at the same dose with CP-060S (300 microg kg(-1)) did not add to the effect of a single treatment of CP-060S. 5. In the ischaemia-induced arrhythmia model, CP-060S (300 microg kg(-1)) significantly decreased the incidence of VF from 75% to 29%, whereas diltiazem (1 mg kg(-1)) was ineffective. 6. These results suggest that CP-060S inhibits both ischaemia- and reperfusion-induced arrhythmia. The combination of the calcium channel blocking effect and the calcium overload inhibition was hypothesized to contribute to these potently protective effects.