Impaired expression of brain natriuretic peptide gene in diabetic rats with myocardial infarction

Accordingly, we induced streptozotocin diabetes in rats and evaluated the effects of ligating the coronary artery to produce myocardial infarct by analyzing hemodynamics and the expression of brain natriuretic peptide (BNP) messenger (m) RNA. Eight-week diabetic rats and age-matched nondiabetic rats underwent ligation of the coronary artery for 1 week. Left ventricular end-diastolic pressure (LVEDP) was not statistically different between diabetic rats (15+/-6 mmHg) and nondiabetic rats (13+/-9 mmHg) 1 week after coronary ligation, size of infarct, systolic blood pressure were also similar in both groups after coronary ligation. The BNP mRNA/beta-actin mRNA ratio in right ventricle of nondiabetic rats with MI was increased to 350+/-60%, however, in diabetic rats with MI, that was slightly increased to 200+/-50% (P < 0.01). The level of BNP mRNA in the left ventricle of diabetic rats with MI was not increased significantly (120+/-30% versus that in diabetic rats without MI), although that in left ventricle of nondiabetic rats with MI was increased to 280+/-40% versus nondiabetic rats without MI (P < 0.01). Cardiac BNP synthesis in diabetic rats completely reverted to control levels after insulin therapy.

Non-surgical treatments for chronic pancreatitis

Non-surgical, less invasive treatment has been required for chronic pancreatitis. We attempted endoscopic approach and extracorporeal shock wave lithotripsy (ESWL) for the treatment of 54 patients with chronic pancreatitis. Endoscopic procedures, such as endoscopic pancreatic sphincterotomy, cystenterostomy and endoprosthesis, were performed in selected 11 patients with pancreatic stones, protein plugs, pseudocysts and main pancreatic duct stenosis. Successful results were obtained in all 11 patients. ESWL was used for the treatment of 43 patients with pancreatic stones. Combined with ESWL, endoscopic treatments were also used in 7 patients. Stone disintegration was achieved in 36/43 patients (83.8%), and complete clearance of main pancreatic duct was obtained in 19 (44.1%). Pain relief was observed in 27/29 (93%). Improvement of exocrine pancreatic function, evaluated by PFD test, was recognized in 10/19 (52.6%). ESWL is a safe and effective treatment for pancreatolithiasis. Endoscopic approach is, when it will be carefully performed, a less invasive and useful treatment for main pancreatic duct stenosis or pancreatic pseudocyst.

Wy-14,643, a peroxisome proliferator, inhibits compensative cell proliferation and hepatocyte growth factor mRNA expression in the rat liver

Previously, we found that a peroxisome proliferator significantly reduced hepatic and plasma hepatocyte growth factor (HGF) levels in male F-344 rats, and that the growth of preneoplastic or neoplastic cells induced by this peroxisome proliferator was markedly inhibited by HGF. Here, we examined the effects of [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio] acetic acid (Wy-14,643), a peroxisome proliferator, on cell proliferation and HGF mRNA levels in the liver of rats after stimulation of compensative cell proliferation. After 2 weeks of treatment with Wy-14,643, hepatic DNA synthesis caused by partial hepatectomy was decreased by 50% compared with untreated controls. DNA synthesis was maintained at the same reduced level for up to 10 weeks. During this period, hepatic HGF mRNA level was also much lower in Wy-14,643-treated rats than untreated controls. Therefore Wy-14,643, a peroxisome proliferator, would inhibit the growth of normal hepatocytes, and then produce an advantageous circumstance for the selective growth of neoplastic or preneoplastic cells.

Asymptomatic brain abscess as a complication of halo orthosis: report of a case and review of the literature

The halo external orthosis has been used extensively for cervical immobilization after spine surgery or trauma, usually without serious complications. However, nine brain abscesses have been reported as complications following the use of halo orthosis. We report on a 53-year-old man who underwent anterior cervical fusion for cervical myelopathy, followed by the application of a halo orthosis. Approximately 4 weeks postfusion, loosening of the right anterior pin was recognized and the pin was tightened, as the pin-site was clean. One week later, purulent material was discharged from the pin hole when the pin was removed after it had loosened again. Enhanced computed tomography (CT) demonstrated an abscess on the right side of the brain. After the administration of antibiotics, the abscess resolved without surgical intervention. We describe asymptomatic brain abscess complicating the use of a halo orthosis and review the clinical features, symptoms, and outcomes; we also discuss the mechanism that induced brain abscess. Most reported cases of abscess have been associated with pin-site infection or tightening after late pin loosening. The present case indicates the importance of early recognition of symptoms and signs associated with brain abscess in patients with a halo orthosis.

Restricted photorelease of biologically active molecules near the plasma membrane

An evanescent wave of ultraviolet light was successfully used to release biologically active molecules from caged compounds in living cells. The evanescent wave was generated by the total internal reflection in a limited region near the plasma membrane attached to the illuminated interface. At first, the photolysis efficiency of the evanescent wave of ultraviolet laser light was studied using caged glutamic acid in vitro. Then, caged Ca2+ introduced in the living cultured cell was similarly photolyzed by the evanescent wave and the resulting elevations of the concentration of intracellular Ca2+ in the proximity of the plasma membrane and in the cytosol were observed with a simultaneously introduced fluorescent calcium indicator. Inositol trisphosphate can also be photoreleased near the plasma membrane, which enables study of the temporal and spatial pathways of signal transduction. The method developed here provides a useful tool for studying signal transduction near the plasma membrane in a living cell.

Newly designed computer controlled knee-ankle-foot orthosis (Intelligent Orthosis)

The authors have developed a knee-ankle-foot orthosis with a joint unit that controls knee movements using a microcomputer (Intelligent Orthosis). The Intelligent Orthosis was applied to normal subjects and patients, and gait analysis was performed. In the gait cycle, the ratio of the stance phase to the swing phase was less in gait with the knee locked using a knee-ankle-foot orthosis than in gait without an orthosis or gait with the knee controlled by a microcomputer. The ratio of the stance phase to the swing phase between controlled gait and normal gait was similar. For normal subjects the activity of the tibialis anterior was markedly increased from the heel-off phase to the swing phase in locked gait. The muscle activities of the lower limb were lower in controlled gait than in locked gait. The ground reaction force in locked gait showed spikes immediately after heel-contact in the vertical component, and unusual patterns were observed at heel-contact in the sagittal and lateral component. Therefore, compared to locked gait, gait with the Intelligent Orthosis is smooth and close to normal gait from the viewpoint of biomechanics. Even in patients with muscle weakness of the quadriceps, control of the knee joint using the Intelligent Orthosis resulted in a more smooth gait with low muscle discharge.

Molecular cloning of rat klotho cDNA: markedly decreased expression of klotho by acute inflammatory stress

We have recently identified a novel gene, termed klotho, that is involved in the suppression of several aging phenotypes. The gene encodes a membrane protein that shares sequence similarity with the beta-glucosidases of bacteria and plants. In this study, we isolated rat klotho cDNA and examined its tissue distribution in rats. The deduced amino acid sequence of rat Klotho protein was 1014 amino acids in length and 94 and 85% homologous to those of mouse and human Klotho proteins, respectively. Northern blot analysis using the rat klotho cDNA probe identified a single transcript of 5.2 kb in size expressed predominantly in the kidney, while RT-PCR detected low levels of expression also in the brain, lung, intestine, and ovaries. During development, klotho expression in the kidney was markedly augmented after birth. Chromosomal localization of rat klotho was mapped to 12q12. Northern blot analysis showed that expression of klotho was markedly decreased by lipopolysaccharide (LPS) in vivo, suggesting that expression of klotho is affected by acute inflammatory stress. The present study leads to a better understanding of the physiologic and pathophysiologic roles of Klotho.

Suppression of apoptotic cell death progressed in vitro with incubation of the chorion laeve tissues of human fetal membrane by glucocorticoid

In the trophoblast layer of the chorion laeve of human fetal membranes obtained by cesarean section at the month of normal parturition, cells with condensed nuclei could be observed by histochemical examination. Incubating fetal membranes at 37 degrees C in vitro in cultivation medium, the frequency of cells with condensed nuclei increased in the chorion laeve, associating with an increase in DNA fragmentation and the population of in situ TUNEL (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-X nick end labeling) staining-positive cells. The progressed apoptotic cell death in the chorion laeve in vitro was suppressed by incubation of the tissue in the presence of glucocorticoids, cortisone or hydrocortisone, which was also demonstrated by DNA fragmentation analysis and in situ TUNEL staining. These results reveal that a substantial proportion of trophoblast cells in the chorion laeve of human fetal membranes are induced to undergo apoptosis at the end of pregnancy, and that the apoptosis progresses rapidly in vitro as the incubation period increases. It is suggested that certain hormones such as glucocorticoid, may be related to the regulation of the apoptosis in human fetal membranes.

Tissue factor is associated with the nonbacterial thrombotic endocarditis induced by a hypobaric hypoxic environment in rats

High-altitude hypoxia causes a hypercoagulable state. In our previous study on the blood coagulation system in rats, nonbacterial thrombotic endocarditis (NBTE) developed after 4-12 weeks' exposure to the equivalent of 5500 m in altitude. We hypothesized that TF (tissue factor)-producing cells in the cardiac valves might be induced by the hypobaric hypoxic environment (HHE) and then trigger NBTE. A total of 170 male Wistar rats were housed in a chamber at the equivalent of 5500 m altitude for 1-12 weeks. We measured TF activity in the plasma and studied morphological changes in the mitral valves using immunohistochemical and immunoelectrical methods for TF protein and in situ hybridization for TF mRNA. After 4 weeks or more of exposure to HHE, 28 of the 56 surviving rats had developed NBTE. After 4-8 weeks' exposure to HHE, the plasma TF activity level was significantly higher than in control rats. There was a significant correlation between plasma TF activity and the incidence of NBTE. After 1 weeks' exposure to HHE, immunoreactivity for TF protein was detected in foamy macrophages and stromal cells in the cardiac valves. In rats with NBTE, TF protein was present in foamy macrophages and spindle stromal cells and focally present in the extracellular matrix. TF mRNA was detected in some foamy macrophages within the thrombus, TF protein was localized to the rough endoplasmic reticulum and plasma membrane of many macrophages, some fibroblasts, and a few endocardial cells. TF is associated with the pathogenesis of the NBTE induced by exposure to HHE. The accumulation of TF-producing macrophages during exposure to HHE may be responsible for initiating thrombus formation.

Idiopathic left ventricular tachycardia with block between purkinje potential and ventricular myocardium

We performed radiofrequency current catheter ablation in a patient with idiopathic LV. While mapping the inferoapical LV septum during tachycardia, spontaneous termination of tachycardia was observed with block between Purkinje (P) potential and ventricular electrogram (P-V block). The cycle length of the tachycardia was associated with prolongation of P-P interval and P-V interval. P potential recording at this site was earliest and at very low amplitude during tachycardia. The radiofrequency current at this site was successful. These findings indicated that Purkinje fiber was a critical part of the tachycardia circuit. Ablation was successful at a site where both an earliest and low amplitude P potential was recorded during tachycardia, and where P-V block that was induced by catheter manipulation was observed during tachycardia.

cDNA cloning and genomic organization of peroxisome proliferator-inducible long-chain acyl-CoA hydrolase from rat liver cytosol

The cDNA for a peroxisome proliferator-inducible long-chain acyl-CoA hydrolase from rat liver cytosol, referred to as rLACH2, was isolated and its genomic structure was determined. The cDNA encoded a 419-amino-acid polypeptide with a calculated molecular weight of 46,011. Sequence analysis identified an active-site serine motif (Gly-x-Ser-x-Gly) common to carboxylesterases and lipases. When expressed in Escherichia coli, the cDNA directed expression of a protein immunoreactive to an anti-rLACH2 antibody with a molecular mass of 47 kDa, identical to that of purified rLACH2. Northern blot analysis showed marked induction of rLACH2 mRNA in the liver after feeding rats with di(2-ethylhexyl)phthalate, a peroxisome proliferator. The rLACH2 gene spanned about 19 kb and comprised 3 exons, the intron/exon boundaries of which were consistent with the donor/acceptor splice rule. A putative peroxisome proliferator response element (AGGTCATGGTTCA) was identified in the 5'-flanking region, suggesting the involvement of peroxisome proliferator-activated receptors in the regulation of rLACH2 gene expression.

Ovarian immune cells express granulocyte-macrophage colony-stimulating factor (GM-CSF) during follicular growth and luteinization in gonadotropin-primed immature rodents

To obtain clues as to whether granulocyte-macrophage colony-stimulating factor (GM-CSF) is related to ovarian physiology, the sites, the gene expression and the production of GM-CSF in the ovary during follicular development and luteinization were studied in equine CG (eCG)-primed immature mice and rats. During follicular development, the expression of GM-CSF mRNA was localized in theca-interstitial tissues, oocytes and granulosa cells of small developing follicles in mice. In the mouse ovary after ovulation, luteal tissues as well as the above components had intense signals for GM-CSF mRNA. Mast cells, which were present mainly in the ovarian medulla, also expressed mRNA for GM-CSF in rats. Immunohistochemical analyses with two different antibodies against murine GM-CSF revealed that GM-CSF-like immunoreactivity was detectable mainly in theca-interstitial, luteal tissues, oocytes and mast cells. Intense GM-CSF positive cells in theca-interstitial and luteal tissues were stained with anti-CD11b antibody in mice. Messenger RNAs for GM-CSF receptor subunits were expressed in mast cells of the medulla and in luteal tissues in rat ovary. The levels of GM-CSF released into the culture media by rat ovarian dispersed cells 1-2 days after eCG treatment were higher than those before the treatment, although no significant change in the levels of ovarian GM-CSF mRNA was detected by reverse transcription-polymerase chain reaction analysis. The secretion of GM-CSF was also increased by treatment of the cells with immune stimulators such as phorbol ester, interleukin-1 and lipopolysaccharide. These data indicate that ovarian macrophages and mast cells in addition to theca-interstitial cells, synthesize and release GM-CSF during ovarian cycles, and that ovarian GM-CSF secreting capacity is enhanced during early stages of follicular development in rodents.

Klotho protein protects against endothelial dysfunction

Arteriosclerosis caused by aging is recognized to be a crucial risk factor of cardiovascular disease. We recently established klotho mouse which causes age-related disorders including arteriosclerosis. However, no information on endothelial function of klotho mouse or the physiological role of klotho protein as a circulating factor is available. In this report, we demonstrate that 50% effective dose of aortic relaxation in response to acetylcholine in heterozygous klotho mice is significantly greater (4 x 10(-5) M) than in wild-type mice (8 x 10(-6) M, n = 7, p < 0.05) and that the vasodilator response of arterioles to acetylcholine is significantly attenuated in heterozygous (20% effective dose; 2 x 10(-6) M) and homozygous klotho mice (>1 x 10(-5) M) as compared with wild-type mice (1 x 10(-7) M, n = 7, p < 0.05). Nitric oxide metabolites (NO-2 and NO-3) in urine are significantly lower in heterozygous klotho mice (142 +/- 16 nmol/day) than wild-type mice (241 +/- 28 nmol/day, n = 13, p < 0.05). Parabiosis between wild-type and heterozygous klotho mice results in restoration of endothelial function in heterozygous klotho mice. We conclude that the klotho protein protects the cardiovascular system through endothelium-derived NO production by humoral pathways.

[Preliminary screening for antiviral AIDS drugs. VIII. Report for fiscal year 1995]

Preliminary screening of antiviral AIDS drugs has been carried out using three different in vitro assay systems. Among 96 samples of different origin tested, two were shown to inhibit the growth of HIV in vitro. One of the positive samples (plant origin) has hopeful signs, as the ranges of effective doses are wider than those of most of positive samples which had been found by us.

Induction of hepatic poly(ADP-ribose) polymerase by peroxisome proliferators, non-genotoxic hepatocarcinogens

Two peroxisome proliferators, [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio] acetic acid (Wy-14,643) or di(2-ethylhexyl) phthalate (DEHP), were given orally to male F-344 rats for up to 78 or 97 weeks. At 1 week, the activity of poly(ADP-ribose) polymerase (pADPRP) was increased 2- and 1.8-fold in the liver of rats treated with Wy-14,643 and DEHP, respectively. The induction of the activity was maintained at 2.5- or 2-fold for up to 52 weeks. The immunoblot and Northern blot analyses revealed that the induction of pADPRP activity would be responsible for the increase in the amount of mRNA. In addition, in the liver tumor induced by Wy-14,643 and DEHP, the pADPRP mRNA level increased 3.6- or 3.7-fold. The magnitude of the increase in the mRNA level was higher than that in the non-tumor portion. These findings suggest that the induction of pADPRP may play an important role in the hepatocarcinogenesis induced by peroxisome proliferators.

Distribution of functional glutamate receptors in cultured embryonic Drosophila myotubes revealed using focal release of L-glutamate from caged compound by laser

During the formation of neuromuscular junctions in Drosophila embryos, glutamate receptors undergo a drastic change in distribution. To study the underlying mechanism of this developmental process, it is desirable to map the distribution of functional receptors with accurate spatial resolution. Since glutamate receptors desensitize within several milliseconds, the agonist must be applied rapidly. To fulfil these requirements we used laser stimulation of a caged compound to release L-glutamate at a focal spot. Since the glutamate receptor channel is permeable to Ca2+, we assayed the change in internal Ca2+ concentration using a Ca2+ indicator, fluo-3. Using this approach, we mapped the distribution of functional glutamate receptors in cultured embryonic Drosophila myotubes and myoblasts. Consistent with previous immunofluorescence studies using an antibody against a glutamate receptor subunit, a large increase of internal Ca2+ concentration was observed when laser stimulation was located close to some nuclei in the myotube. No change was detected when the laser stimulus was applied over any regions of the myoblasts. No increase of the internal Ca2+ concentration in myotubes was observed when the external solution contained either glutamate at a desensitizing concentration (1 mM) or a glutamate receptor channel blocker, argiotoxin (1 microg/ml). These results indicate that a rise in intracellular Ca2+ concentration can be used to show the distribution of the functional receptor on the muscle surface membrane.

[Clinical assessment of contrast-enhanced ultrasonography for the diagnosis of gall bladder diseases]

We evaluated the efficacy of contrast-enhanced ultrasonography (CEUS) with intra-arterial injection of CO2 microbubbles in 37 cases of gall bladder diseases. CEUS clearly visualized arterial flow and vascularity in every lesions without debris and gave us the precise information of vascular structure for the differential diagnosis of gall bladder tumors. For example, highly bifurcated tumor vessels and strong enhancement was observed in gall bladder cancer and we could detect relatively strong enhancement along the lumen with lack of enhancement of Rokitansky-Aschoff sinus in localized-type adenomyomatosis. Though CEUS is now an invasive modality, it will enable us to understand the non-invasive modality such as color doppler imaging with intra-venous administration of microbubbles in the future.

Morphological, biochemical and molecular biological characteristics of a granulocyte colony-stimulating factor-producing human eccrine carcinoma cell line

We describe here a newly established cell line from an eccrine carcinoma which produced an abundant amount of granulocyte colony-stimulating factor (G-CSF). An eccrine carcinoma of the scalp of a 69 year-old-Japanese female had metastasized to the pleura. Clinically, she had marked neutrophilia (up to 60,000/mm3), and a high level of G-CSF (38.7 x 10(3) pg/ml) was detected in the pleural effusion, as determined by enzyme-linked immunosorbent assay (ELISA). We established a cell line in vitro and maintained the cells in culture for 30 months in 90 subcultures. We investigated whether these tumor cells were able to produce G-CSF in culture and found that they were. We also found that the amount of G-CSF produced paralleled the rise in cell number (26.5 x 10(3) pg/ml at confluency). When culture media were administered to rabbits (25 ml/rabbit), the amount of circulating neutrophils increased until the number was equal to or greater than that resulting from injection of recombinant human G-CSF (rhG-CSF)(75 micrograms). This effect persisted for 7 days. When tumors were induced in SCID and nude mice by injecting cultured cells (1 x 10(7) cells/mouse), the number of circulating neutrophils also correlated well with tumor size in these mice (200,000/mm3, 3 cm tumor). After tumor removal, the neutrophil number returned to normal within 30 days. G-CSFmRNA in cultured, cells was detected by RT-PCR. Based on these results, it was confirmed that the marked neutrophilia observed in the patient was caused by the tumor-generated G-CSF. This is the first G-CSF-producing cell line developed from a cancer of the skin.

[A case of Sairei-to-induced pneumonitis diagnosed by lymphocyte stimulation test of bronchoalveolar lavage fluid]

A 51-year-old woman was admitted with fever, cough and dyspnea. She had been taking Sairei-to, a traditional Chinese medicine, for 2 months. On admission, chest X-ray revealed a ground-glass appearance in the lung fields bilaterally and serum LDH was elevated. A differential cell count of the bronchoalveolar lavage fluid (BALF) showed that lymphocytes were increased, with a decreased ratio of CD4/CD8 cells. A lymphocyte stimulation test (LST) for Sairei-to using the lymphocytes in BALF was a positive, although a test of peripheral blood was negative. Sairei-to-induced pneumonitis was diagnosed based on the clinical course, laboratory findings, BALF cell analysis and LST of BALF. Only 4 cases of pneumonitis due to Sairei-to have been reported. This case suggests that LST of BALF is useful for diagnosing drug-induced pneumonitis.

Effect of the side-chain structure on the specificity of beta-oxidation in bile acid biosynthesis in rat liver homogenates

3Alpha, 7alpha, 12alpha-trihydroxy-5beta-cholestan-26-oic acid (C27-5beta-cholestanoic acid) derivatives with different carbon-number side chains were incubated with rat liver 800 g supernatant to study the effect of the side-chain length on the beta-oxidation system in bile acid biosynthesis. The intermediate alpha, beta-unsaturated and beta-hydroxylated bile acids, and the corresponding degradation products, were quantitatively determined by gas chromatography. The longer side-chained derivatives (C28- and C29-5beta-cholestanoic acids) were converted into corresponding sidechain degradation products, and the alpha,beta-unsaturated and beta-hydroxylated intermediates were also produced. On the other hand, the shorter side-chained derivative (C26-5beta-cholestanoic acid) only gave alpha,beta-unsaturated intermediate. The total formation of intermediates and degradation products from corresponding substrates was in the order of C27- > C28- > C29- > C26-5beta-cholestanoic acids. In the case of clofibrate-treated rat liver 800 g supernatant, the formation of intermediates and final degradation products from C28- and C29-5beta-cholestanoic acids increased significantly. These longer side-chained analogues seemed to be subjected to beta-oxidation system(s) induced with clofibrate treatment. The effect of a terminal methyl group in the side chain of 5beta-cholestanoic acid on the oxidation system was also investigated using 3alpha, 7alpha, 12alpha-trihydroxy-27-nor-5beta-cholestanoic acid derivatives as enzymatic substrates. These derivatives gave corresponding side chain degradation products, but the formation of intermediates was not detected. The formation of side chain cleavage products from 27-nor-5beta-cholestanoic acid derivatives increased to 10 to 25-fold that of the controls by treatment with clofibrate. The results suggested that the beta-oxidation system for 27-nor-5beta-cholestanoic acid derivatives was different from that for C27-5beta-cholestanoic acid, despite their bile acid steroidal structure.

Mutation of the mouse klotho gene leads to a syndrome resembling ageing

A new gene, termed klotho, has been identified that is involved in the suppression of several ageing phenotypes. A defect in klotho gene expression in the mouse results in a syndrome that resembles human ageing, including a short lifespan, infertility, arteriosclerosis, skin atrophy, osteoporosis and emphysema. The gene encodes a membrane protein that shares sequence similarity with the beta-glucosidase enzymes. The klotho gene product may function as part of a signalling pathway that regulates ageing in vivo and morbidity in age-related diseases.

Biologically active clerodane-type diterpene glycosides from the root-stalks of Dicranopteris pedata

The molecular structure of the biologically active diterpene alcohol isolated previously from the root-stalks of Dicranopteris pedata and Gleichenia japonica was confirmed to be (6S,13S)-cleroda-3,14-diene-6,13-diol by an X-ray crystallographic analysis, together with application of the octant rule to the Cotton effect observed in the CD spectrum of its 6-keto derivative. Further investigation of the root-stalks of D. pedata has resulted in the isolated two new glycosides, which were characterised as (6S,13S)-6-O-[beta-D-glucopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl] 13-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-fucopyranosyl] cleroda-3,14-diene and (6S,13S)-6-O-[beta-glucopyranosyl]-13-O-[beta-fucopyranosyl-(1-->2) -alpha-rhamnopyranosyl]-cleroda-3,14-diene. Of these two glycosides, the former glycoside accelerated the growth of the stems of lettuce and inhibited the growth of the roots.

Influence of extracellular H+ and Ca2+ on Ro 22-9194-induced block of sodium current in cardiac myocytes

1. Ro 22-9194 reduced the Na current in ventricular myocytes in either a tonic block or phasic block manner. 2. Ro 22-9194 had a higher affinity to the inactivated state (Kdi = 10.3 microM) than to the rested state (Kdrest = 180 microM). 3. Extracellular acidification enhanced the tonic block but reduced the phasic block. 4. Elevation of extracellular Ca2+ inhibited the enhancing effects of extracellular acidification. 5. These findings suggest that Ro 22-9194 strongly inhibits Na+ channels of the ventricular myocytes of the diseased hearts, characterized by the depolarized cell membranes and by acid conditions.