Myxopapillary ependymoma of the temporal lobe--report of a rare case of temporal lobe epilepsy

Myxopapillary ependymomas are a benign variant of ependymomas, occurring almost exclusively in the cauda equina region. We report an extremely rare case of myxopapillary ependymoma located in the left anterior temporal lobe. A 22-year-old man is presented with intractable seizures of 2 years duration with no focal neurologic deficits. Imaging of the brain revealed a well-circumscribed heterogeneous mass in the left anterior temporal pole with no connection to the ventricles. Imaging of the spine was normal. The patient underwent surgical removal of the tumor and at follow-up 4 months after surgery, there was improvement in his memory and speech along with complete cessation of seizures. Microscopic examination revealed the tumor to be a myxopapillary ependymoma, further confirmed by histochemical and immunohistochemical stains. To the best of our knowledge, this is the first documentation of myxopapillary ependymoma at this location and consequently, the first case to clinically present as intractable temporal lobe epilepsy.

Merosin negative congenital muscular dystrophy: a short report

We report a rare case of an infant with congenital muscular dystrophy who presented at birth with marked generalized hypotonia and normal mental development. Creatinine phosphokinase (CPK) level was markedly raised; however no white matter abnormalities were detected by brain imaging techniques. Immunohistochemical staining for merosin (laminin alpha 2) was negative, thereby confirming merosin-deficient congenital muscular dystrophy.

Primary osteosarcoma of the skull. A report of 3 cases

Osteosarcomas are malignant bone tumors, which commonly affect the long bones of young adults. Primary osteosarcomas of the skull are exceedingly rare. We herein report 3 cases of primary osteosarcoma of the skull involving the calvaria, diagnosed over a period of 8 years at the Department of Pathology of our Institute.

Cerebrotendinous xanthomatosis: neuroimaging findings in two siblings from an Indian family

Cerebrotendinous xanthomatosis (CTX) is exceptionally rare in the Indian population. We present and discuss the clinical, radiological and histopathologic findings in 2 siblings with CTX. Both the patients had juvenile cataract, mental retardation and marked cerebellar ataxia. The Achilles tendon swelling was present in only 1 patient (Case 2). MR imaging showed typical bilateral and symmetrical involvement of the dentate nuclei, inferior olives, brainstem and cerebellar hemispheric white matter. Although the diagnosis of CTX was made in the 3rd decade in both our cases, early diagnosis is possible if neuroimaging is done in the early course of the disease.

Cytodiagnosis of anaplastic astrocytoma with metastasis to the cerebrospinal fluid in a neonate--a case report

A case of left cerebral hemispheric anaplastic astrocytoma with metastasis to the cerebrospinal fluid in a 50-day-old male child diagnosed on cytology and later confirmed by histological examination is reported.

Clinicopathological study of spinal teratomas. A series of 10 case

AIM

Sacrococcygeal teratomas are common in children, but intramedullary spinal teratomas are rare. We report a series of 10 cases of spinal teratomas, which, to the best of our knowledge, is the largest series of intramedullary teratomas.

METHODS

During a period of 15 years (1987-2001) 10 cases of spinal teratomas were diagnosed in our department. The clinical profile, radiological data and histopathological slides were reviewed.

RESULTS

Age ranged from 10 months to 51 years (mean 23.5 years) with male predominence. Duration of symptoms varied from 5 months to 20 years (mean 4.1 years). The most common symptoms were weakness of lower limbs, backache and urinary bladder involvement. Radiologically, these were heterogenous lesions with fat signal and areas of calcification. Surgery is the treatment of choice. Only 1 case recurred after 9 years of operation.

CONCLUSION

Although there are no specific features on imaging of intramedullary teratomas, solid and cystic morphology, fat signal and areas of calcification are some of the helpful features. Most of these lesions are diagnosed on histopathological examination after surgery. Surgery is the treatment of the choice.

Large cystic fibrous dysplasia of the temporal bone: case report and review of literature

Fibrous dysplasia is an uncommon benign disorder of unknown aetiology. It most likely represents a disorder of normal bone development. As it may occasionally involve the temporal bone, and encroach on the middle cranial fossa, it is of interest to the neurosurgeon. Fibrous dysplasia of the cystic variety is very uncommon. We report a case of a large cystic fibrous dysplasia involving predominantly the squamous temporal bone. The radiology and histology are discussed, and its differentiation from other lesions.

A melanotic desmoplastic medulloblastoma: report of a rare case and review of the literature

A 28-year-old man had a desmoplastic medulloblastoma in the vermis and left cerebellum. This tumor was composed of nodular, reticulin-free zones (pale islands) surrounded by densely packed, highly proliferative cells that produced a dense intercellular reticulin network. Some of the cells were heavily pigmented, and this pigment proved to be melanin. Adult age, desmoplastic nature, and melanin pigmentation are some of the rare features of this tumor that need documentation. Further, this pigment was in the primitive cells, unlike in the published cases, in which it was present in the tubular or tubulopapillary component. To the best of our knowledge, this is the first published case of desmoplastic pigmented medulloblastoma, and the patient is the oldest reported to have this tumor.

Selective mitochondrial KATP channel activation by nicorandil and 3-pyridyl pinacidil results in antiarrhythmic effect in an anesthetized rabbit model of myocardial ischemia/reperfusion

The roles of cardiomyocyte sarcolemmal ATP-sensitive K+ (KATP) and mitochondrial KATP channels in cardioprotection and antiarrhythmic activity induced by KATP channel openers remain obscure. However, it has been suggested that the mitochondrial KATP channels are involved as a subcellular mediator in cardioprotection afforded by ischemic preconditioning. In the present study, we investigated the effects of the administration of non-hypotensive doses of ATP-sensitive K+ channel (KATP) openers (nicorandil and 3-pyridyl pinacidil), a specific mitochondrial KATP channel blocker (5-hydroxydecanoate) and a specific sarcolemmal KATP channel blocker (HMR 1883; 1-[5-[2-(5-chloro-o-anisamido)ethyl]-2-methoxyphenyl]sulfonyl-3- methylthiourea) prior to and during coronary occlusion, as well as prior to and during post-ischemic reperfusion, on survival rate, ischemia-induced and reperfusion-induced arrhythmias and myocardial infarct size in anesthetized albino rabbits. The thorax was opened in the left 4th intercostal space and after pericardiotomy the heart was exposed. In Group I (n = 80), occlusion of the left main coronary artery and hence, myocardial ischemia-induced arrhythmias were achieved by tightening a previously placed loose silk ligature for 30 min. In Group II (n = 186), arrhythmias were induced by reperfusion following a 20 min ligation of the left main coronary artery. In both Group I and Group II, early intravenous infusion of nicorandil (100 micrograms/kg bolus + 10 micrograms/kg/min), 3-pyridyl pinacidil (3.0 micrograms/kg bolus + 1.0 microgram/kg/min), HMR 1883 (3 mg/kg)/nicorandil and HMR 1883 (3 mg/kg)/3-pyridyl pinacidil, just prior to and during ischemia, increased survival rate (75%, 67%, 86% and 75% vs. 60% in the control subgroup in Group I; 67%, 75%, 75% and 67% vs. 43% in the control subgroup in Group II), significantly decreased the incidence and severity of life-threatening arrhythmias and significantly decreased myocardial infarct size. However, late intravenous administration of nicorandil or 3-pyridyl pinacidil at the onset of and during reperfusion did not increase survival rate nor confer any antiarrhythmic or cardioprotective effects. The antiarrhythmic and cardioprotective effects of both nicorandil and 3-pyridyl pinacidil were abolished by pretreating the rabbits with 5-hydroxydecanoate (5 mg/kg, i.v. bolus), a selective mitochondrial KATP channel blocker, but not by pretreatment with HMR 1883 (3 mg/kg). In the present study, higher levels of malondialdehyde (MDA) and lower levels of reduced glutathione (GSH) and superoxide dismutase (SOD) in the necrotic zone of myocardium in all sixteen subgroups in Group II suggest little anti-free radical property of nicorandil and 3-pyridyl pinacidil. Therefore, we may conclude that intervention by intravenous administration of nicorandil and 3-pyridyl pinacidil (through the selective activation of mitochondrial KATP channels), increases survival rate and exhibits antiarrhythmic and cardioprotective effects during coronary occlusion and reperfusion in anesthetized rabbits, when administered prior to and during coronary occlusion. The mitochondrial KATP channel may be considered to be a potentially important site of cardioprotection and antiarrhythmic activity.

A comparative study of classical vs. desmoplastic medulloblastomas

Classical and desmoplastic medulloblastomas (MBs) have been suspected to be biologically different, though comparative studies on markers of biological aggressiveness in these two variants are sparse in the literature. 87 classical and 43 desmoplastic variants of MB were studied with respect to clinical and histological characteristics, MIB-1 labeling index (MIB-1 LI), apoptotic index (AI), ratio of AI to MIB-1 LI, expression of p53 and Bcl-2 protein and 3-year progression-free survival. The only differences documented between the variants were with regard to age distribution and location. Thus, classical histology cases occurred predominantly in children and 80% were midline in location. In contrast, lateral location was seen more frequently with tumors of desmoplastic histology, which occurred in an almost equal distribution between children (56%) and adults (44%). No difference was noted between the variants with regard to proliferation index, apoptotic index, their ratio on or their molecular controls (p53 and Bcl-2). This was reflected in the clinical outcome wherein no significant difference was observed in the 3-year progression-free survival between the variants. It is concluded that the two histological variants of medulloblastoma are not different with regard to biological parameters of aggressiveness. The growth rate and clinical outcome in medulloblastomas have no correlation with the histological variant.

Chronic subdural haematoma and the enigmatic eosinophil

The membranes from 50 cases of chronic subdural haematomas were examined histologically and correlated with the duration of the lesion. Cases were divided into three groups based on duration from time of trauma and/or onset of clinical symptoms to date of surgery - Group I: 1 to 30 days, Group II: 31 to 90 days and Group III: >90 days. Infiltration with eosinophils was observed in the vascularised and hyalinised granulation tissue of the subdural membrane in 30 of the 50 cases (60%). There was a trend to correlation both of the frequency and the extent of eosinophilic infiltration with duration of haematoma. Thus, eosinophils were encountered in about half the cases with duration up to 3 months which increased to 80% in cases with duration more than 3 months. The extent of eosinophilic infiltration (mild, moderate or severe) also appeared to correlate with duration of haematoma in that mild infiltration was more common in Group I cases while moderate to severe infiltration were more frequently observed in Group II and III cases. No correlation was observed of the eosinophilic infiltrate with age and sex of the patients or with presence of other cellular inflammatory components of the membrane. Interestingly, a finding hitherto unreported in English literature was the demonstration of mast cells in 7 of 16 membranes (44%) which had been stained using toluidine blue. It is possible that the eosinophils appear at this unusual site due to chemotactic stimulus abetted by these mast cells as well as lymphocytes and haemosiderin pigment. The eosinophils may have an important role in the repair and healing process of these membranes.

Intramedullary tuberculoma of the spinal cord: a series of 10 cases

OBJECTIVE

Involvement of vertebral column is common in tuberculosis but intramedullary tuberculomas are rare. We report a series of ten cases of intramedullary tuberculomas, which, to the best of our knowledge, is the largest series of biopsy proven intramedullary tuberculomas in English literature.

METHODS

During a period of 16 years (1985-2000), ten cases of intramedullary tuberculomas were diagnosed in our department. Of these, eight cases were histologically proven intramedullary tuberculomas. The clinical profile, radiological data and histological slides were reviewed.

RESULTS

Age ranged from 18 to 45 years (mean 29.7 years) and there was slight male preponderance (six men, four women). Duration of symptom varied from 3 to 20 months (mean 11.5 months). All of them presented with motor weakness and sensory impairment. Most common site of involvement was dorsal cord followed by cervical, cervicodorsal and dorsolumbar regions. Three patients had associated involvement of lungs, cervical lymphnodes, and brain, and one patient had past history of tuberculous meningitis. Two patients were treated conservatively but surgical excision was done in eight cases followed by medical treatment.

CONCLUSION

Radiologically, intramedullary tuberculomas should be differentiated from other space occupying lesions (SOL) to avoid unnecessary surgery especially in those patients with tuberculosis of the other organs. The incidence of intramedullary tuberculomas is likely to increase with a rise in the incidence of AIDS.

Recurrent astrocytic tumours--a study of p53 immunoreactivity and malignant progression

Recurrence and progression to higher grade lesions are characteristic of the clinical course of astrocytic tumours. Though p53 gene mutation is an important initiating event in astrocytic tumourigenesis, its role in malignant progression remains controversial. We have therefore analysed p53 protein expression in paired histological samples from 48 cases of astrocytic tumours and their recurrences--29 diffuse astrocytoma, 10 anaplastic astrocytoma and 14 glioblastoma multiforme (GBM). Malignant progression at recurrence was noted in 93% of diffuse and 64% of anaplastic astrocytomas. An association was observed of p53 protein immunopositivity and malignant progression at recurrence. Thus, 27 of 48 (56%) primary tumours were initially p53 positive, while in recurrent tumours associated with malignant progression this frequency increased to 71% (34/48 cases). This was because seven of the 13 cases (4/8 diffuse and 3/5 anaplastic astrocytoma) that were initially p53 negative acquired immunopositivity on malignant progression at recurrence. In contrast, none of the 19 tumours that recurred to the same grade showed any change of p53 status at recurrence. Furthermore recurrence was associated with increase in the percentage of p53 immunopositive cells (p53 labelling index), which was also higher in tumours with progression. This new acquisition of p53 immunopositivity on progression at recurrence has not been documented in earlier studies in English language literature, though increase in p53 LI has been documented. Thus, this study conclusively indicates the role of p53 in malignant progression of astrocytic tumours. Also, it suggests a potential role of p53 LI in predicting malignant progression at recurrence because the highest initial LI was noted in those tumours which progressed to GBM as compared with those which recurred to the same grade or progressed to anaplastic astrocytoma. No correlation could, however, be demonstrated between p53 immunoreactivity and interval to recurrence.

Brain biopsy in Creutzfeldt-Jakob disease: evolution of pathological changes by prion protein immunohistochemistry

The formation of protease-resistant prion protein (PrPsc) is considered to be an early event in the pathogenesis of Creutzfeldt-Jakob disease (CJD) and hence its demonstration in brain biopsies by immunohistochemistry is considered diagnostic. We analysed eight brain biopsies from the frontal cortex collected from different parts of India from cases diagnosed as CJD on clinical and pathological grounds for the expression of prion protein (PrP). The duration of illness in these cases varied from 2 months to 1 year. Immunohistochemistry was carried out on paraffin sections using two different clones (KG9 and 3F4) of monoclonal antibodies to PrP. Although all eight cases showed classical features of spongiform encephalopathy of varying severity, only five of the eight cases revealed PrP(sc) in the brain tissue. The immunolabelling was focal and all areas with spongiform change were not labelled. A temporal evolution in the staining pattern was evident - particulate diffuse labelling (synaptic type) in early stages (2 months), perivacuolar deposits in intermediate stages (5-6 months), and dense plaques in late stages (12 months).

Osteochondroma of the spine: an enigmatic tumor of the spinal cord. A series of 10 cases

BACKGROUND

The aim of this study was to evaluate clinical, radiological and pathological features of vertebral osteochondromas with compressive myelopathy and to review the relevant English literature. Osteochondro-mas are common benign bony lesions of long bones but involvement of spine by solitary osteochondroma and its presentation as compressive myelopathy is rare. Most of the literature is in the form of case reports.

METHODS

During a period of 20 years (1980-1999), 10 cases of osteochondromas of the spine were encountered. Clinical, radiological and pathological features were reviewed.

RESULTS

The age ranged from 13 to 45 years (mean 25.3 years) and all except 1 were males. In 8 cases the pathology involved the cervical spine and in two cases dorsal spine was involved. All patients presented with progressive motor sensory deficit of 6 months to 30 years duration (mean 3.9 years). Decompressive laminectomy was carried out in all the patients. Fortunately, gradual and complete recovery was observed in all of them.

CONCLUSIONS

Osteochondromas of the spine are not as rare as reported in the literature. In a young patient of compressive myelopathy this possibility should be considered. Magnetic resonance imaging, computed tomography and CT myelogram are useful in evaluating the size and extent of the lesion for subsequent surgical planning.

Antimicrobial drug use in dermatology in a teaching hospital in western Nepal

Medical audit is supposed to oversee, monitor and analyse standards of medical treatment at all levels of the healthcare delivery system. This study was undertaken to monitor the prescribing of antimicrobial drugs for patients seeking treatment in the dermatology outpatient department of the Manipal Teaching Hospital in Nepal. A total of 292 dermatology prescriptions of patients attending the dermatology OPD were collected between July 2000 and June 2001. Prescriptions for antimicrobial agents were separated from the total prescriptions collected, and evaluated. There were more female patients (58.2%) than male (41.8%) in our study; most were in the 21-40 year age group. The commonest cutaneous infections were acne (15.8%) followed by fungal infections (14.8%). Of the 292 prescriptions audited, 149 contained antimicrobial agents, constituting 36% of the total number of drugs prescribed. Of 256 antimicrobials prescribed, 63% were topical and 37% systemic; 5% were generic, 29% were from the essential drug list of Nepal, and 15% were fixed-dose combinations. Most of the patients received one or two antimicrobials, 50% of which were antibacterials and 40% antifungals. Though the selection of antimicrobial drugs used in dermatology was largely rational, anomalies were observed, and these issues were discussed with clinicians in relation to various aspects of drug use. The results indicate there is scope for improving prescribing habits. A periodic audit of drug prescribing is desirable in rationalising prescribing practice.

Lipomedulloblastoma in a child: a controversial entity

Lipomedulloblastoma is regarded as a distinct entity that occurs exclusively in adults and has a low proliferative potential and a favorable outcome. We describe a rare case of lipomedulloblastoma in a 6-year-old female child showing a high labeling index that needs documentation. The various hypotheses of adiposal change are discussed.

Microneural anastomosis with fibrin glue: an experimental study

An experimental study was designed to compare the histological analysis of nerve anastomosis with 10-0 microsurgical sutures and fibrin adhesive. Wistar albino rats' sciatic nerves were transected and repaired either with fibrin adhesive-Beriplast P (M/s Centeon-Cadila Health Care) or with 10-0 monofilament microsutures. Histological assessment was performed at 10, 20, 30, 60 and 90 days after surgery. Functional recovery of the sciatic nerves started at two months and was near normal by three months. Separation of the stumps did not occur in any of the glued nerves. Histological evaluation showed no appreciable difference in the outcome of nerve regeneration after microsurgical repair using sutures or fibrin tissue adhesive. However, inflammation and granuloma formation were appreciated at the suture site, which presented a focal hindrance to myelin and axonal regeneration. Fibrin glueing is attractive for clinical purposes, since it is simpler and less time consuming than suturing.

Effects of nicorandil administration on survival rate and arrhythmias during reperfusion in anesthetized rabbits

The aim was to study the effects of nicorandil (an ATP-sensitive K+ channel opener) and tolbutamide (an ATP-sensitive K+ channel blocker) on reperfusion-induced arrhythmias in pentobarbitone and ketamine anesthetized rabbits. Arrhythmias were induced by reperfusion for 20 min following a 15-min ligation of the left main coronary artery with a silk ligature. Rabbits were pretreated with nicorandil (0.47, 0.93 or 1.86 mg/kg i.v.) or tolbutamide (180 mg/kg i.p.) or vehicle (dimethylsulfoxide/saline) before the coronary artery occlusion. In the control group (n = 10), only 60% of the animals survived during reperfusion. Intravenous pretreatment with 0.47, 0.93 or 1.86 mg/kg of nicorandil increased the survival rate to 86% (n = 7), 75% (n = 8) and 86% (n = 7), respectively. Nicorandil pretreatment significantly decreased the incidence and duration of reperfusion-induced life-threatening arrhythmias and increased the number of animals that survived without developing any arrhythmia. Tolbutamide pretreatment was associated with a decreased survival rate of 50% (n = 12) and an increase in the incidence and duration of reperfusion-induced arrhythmias. Pretreatment with nicorandil may result in protection against reperfusion-induced arrhythmias and increased survival in anesthetized rabbits.

Clear cell odontogenic carcinoma: a diagnostic dilemma

A 26-year-old man presented with a swelling in the right side of face and CT scan revealed a destructive tumor in the right maxilla. Tumor recurred within 5 years of its excision and histopathological examination revealed a clear cell odontogenic carcinoma. The rarity of this tumor, occurrence in maxilla and young age of the patient are some of the rare features which need documentation. The importance of its diagnosis and various differential diagnoses are discussed.

Alteration of a sequence with homology to human endogenous retrovirus (HERV-K) in primary human glioma: implications for viral repeat mediated rearrangement

We had earlier demonstrated that a comparison of DNA fingerprinting profiles of tumor and corresponding normal DNA from the same patient by random amplified polymorphic DNA (RAPD) analysis can readily demonstrate alterations in tumor DNA [Gene 206 (1998) 45 and J. Neuro Oncol. 48 (2000) 1]. These alterations could be used to identify changes in tumor DNA where the prior identity of the locus was not known. In this study, we report the identification, cloning and characterization of a RAPD amplified fragment which was lost in a glioma, a grade IV glioblastoma multiforme (GBM). Comparison of the RAPD profile of tumor and corresponding leucocyte DNA revealed several differences between the two. These included a band of 443 bases, which was demonstrated in the normal, but not in tumor DNA. On sequencing, this band was found to be homologous with a group of SINE sequences, which are probably derived from the human endogenous retrovirus-K (HERV-K). Homology search also reveals that HERV-K-derived sequences are interspersed, amongst others, in the tumor suppressor gene BRCA2 and the DNA repair gene XRCC1. Of particular interest is the inverted repeat pattern of HERV-derived sequences in the genes. While not demonstrating a cause effect relationship, this highlights the possible role of such virus-derived sequences in gene inactivation by recombination during tumorigenesis.

Diastematomyelia associated with ectopic dysplastic renal tissue--report of a rare case

BACKGROUND

Presence of heterotopic dysplastic renal tissue in the lumbosacral region is an extremely uncommon condition.

CASE REPORT

We report the first case of diastematomyelia associated with ectopic renal tissue. A 10-month-old male child presented with lipomeningomyelocele associated with spina bifida in the lumbosacral region, and the lipoma was excised. Imaging of the spine at 5 years of age showed spina bifida, bony diastematomyelia, lipomeningomyelocele and a small intraspinal cystic lesion. The boy was then operated upon at the age of 5 years, and histopathological examination of the cystic lesion revealed ectopic dysplastic renal tissue.

Spectrum of floppy children in Indian scenario

OBJECTIVE

To study the clinical profile of paralytic floppy infants undertaking available investigations and detect the frequency of exon7 of survival motor neuron (SMNT) gene deletion among the spinal muscular atrophy (SMA) cases.

DESIGN

Descriptive study.

SETTING

Tertiary care teaching hospital.

SUBJECTS

70 paralytic floppy infants (40 males/30 females) with age less than 13 years were included in the study. Exclusion criteria included central hypotonia of any cause. Detailed clinical evaluation was done followed by serum creatine phosphokinase levels, electrophysiological studies, muscle biopsy including immunohistochemistry and electron microscopy. Exon7 of SMNT gene deletion studies was done by PCR.

RESULTS

Final diagnosis of SMA was assigned to 37 patients followed by congenital myopathy (n = 7), cogenital muscular dystrophy (n = 5), mitochondrial myopathy (n = 4), neuropathies (n = 5) and diaphragmatic SMA (n = 1). Only 15.7% of cases remained unclassified. When EMG was correlated with final diagnosis, it was 80.6% and 75% sensitive and 68.8% and 87.5% specific for neurogenic and muscle disease, respectively. Muscle biopsy revealed neurogenic atrophy in 47.8% cases followed by normal in 37.3% and myopathic pattern in 14.97% cases. Exon7 of SMNT gene was deleted in only 50% of SMA cases.

CONCLUSIONS

Spinal muscular atrophy was the commonest cause of floppy children. The low rate of SMNT gene deletion detected needs confirmation with further studies.

Effects of administration of nicorandil or bimakalim prior to and during ischemia or reperfusion on survival rate, ischemia/reperfusion-induced arrhythmias and infarct size in anesthetized rabbits

We investigated the effects of administration of non-hypotensive doses of ATP-sensitive K+ channel (KATP) openers (nicorandil and bimakalim), and a specific mitochondrial KATP channel blocker (5-hydroxydecanoate) prior to and during coronary occlusion as well as prior to and during post-ischemic reperfusion on survival rate, ischemia-induced and reperfusion-induced arrhythmias and myocardial infarct size in anesthetized albino rabbits. The thorax was opened in the left fourth intercostal space and after pericardiotomy the heart was exposed. In Part I, occlusion of the left main coronary artery and hence, myocardial ischemia-induced arrhythmias were achieved by tightening a previously placed loose silk ligature for 30 min. In Part II, arrhythmias were induced by reperfusion following a 20-min ligation of the left main coronary artery. In Part I, early intravenous infusion of nicorandil (100 microg/kg bolus + 10 microg/kg per min) or bimakalim (3 microg/kg bolus + 0.1 microg/kg per min) just prior to and during ischemia increased survival rate (75% and 67% vs. 60% in the control group), significantly decreased the incidence and severity of life-threatening arrhythmias and significantly decreased myocardial infarct size. In Part II also, early intervention by intravenous infusion of nicorandil (100 microg/kg bolus + 10 microg/kg per min) or bimakalim (3 microg/kg bolus + 0.1 microg/kg per min) just before and during ischemia increased survival rate (86% and 75% vs. 55% in the control group), significantly decreased the incidence and severity of life-threatening arrhythmias and significantly decreased myocardial infarct size. However, late intravenous administration of nicorandil or bimakalim at the onset and during reperfusion did not increase survival rate nor confer any antiarrhythmic or cardioprotective effects. The antiarrhythmic and cardioprotective effects of both nicorandil and bimakalim were abolished by pretreating the rabbits with 5-hydroxydecanoate (5 mg/kg, i.v. bolus), a selective mitochondrial KATP channel blocker. In conclusion, intervention by intravenous administration of nicorandil and bimakalim (through the activation of mitochondrial KATP channels), increased survival rate and exhibited antiarrhythmic and cardioprotective effects during coronary occlusion and reperfusion in anesthetized rabbits when administered prior to and during coronary occlusion.