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M Ogihara

Publications and source records attributed to M Ogihara.

At least 19 recordsLinked to original sources
PubMed2000

Stimulation of DNA synthesis and proliferation by prostaglandins in primary cultures of adult rat hepatocytes.

We studied the effects of several prostaglandins on DNA synthesis and proliferation in serum-free primary cultures of adult rat hepatocytes. Maintained in short-term cultures (i.e., 3.5 h), the hepatocyte parenchymal cells synthesized DNA and proliferated in the presence of various prostaglandins in a dose-dependent manner. The half-maximal effective concentrations (ED(50)) of prostaglandin F(2alpha), prostaglandin E(1), prostaglandin E(2) and prostaglandin I(2) for proliferation were estimated to be 1.7 x 10(-9), 2.3 x 10(-8), 2.7 x 10(-8) and 3.3 x 10(-9) M, respectively. Prostaglandin E(2) and prostaglandin I(2) produced greater maximal responses than did either prostaglandin E(1) or prostaglandin F(2alpha). The cells responded only weakly to prostaglandin D(2). The stimulatory effects of 10(-6) M prostaglandin E(1) and 10(-6) M prostaglandin E(2) on hepatocyte DNA synthesis and proliferation were inhibited by a specific antagonist of the EP(1) receptor, 8-chlorodibenz[b, f][1, 4]oxazepine-10(11H)carboxylic acid, 2-[3-[(2-furanylmethyl)-thio]-1-oxopropyl]hydrazide (SC-51322; 10(-6) M). Specific inhibitors of signal transducing elements (e.g., 1-[6-[17beta-3-methoxyestra-1, 3, 5(10)-trien-17-yl]amino] hexyl]-1H-pyrrol-2,5-dione (U-73122); 10(-6) M), 10(-6) M verapamil, 5 x 10(-6) M genistein) almost completely blocked the growth-promoting effects of the prostaglandins. These results suggest that prostaglandins stimulate hepatocyte DNA synthesis and proliferation by their own receptors and exert their effects through both phospholipase C/Ca(2+) and receptor tyrosine kinase pathways.

Animals↗
PubMed2000

Potentiation of effects of anticancer agents by local electric pulses in murine bladder cancer.

Electrochemotherapy is a novel cancer treatment in which electric pulses (EP) are used as a means of delivering anticancer agents to the cytoplasm of cancer cells (electroporation). The present study evaluates whether electrochemotherapy has in vitro and in vivo anticancer effects in murine bladder cancer. Using mouse bladder tumor cells (MBT-2 cells), in vitro electrochemotherapy was performed by applying EP to the cell suspension immediately after the addition of anticancer agents. The cytotoxicity of adriamycin (ADM), bleomycin (BLM) and cis-diamminedichloroplatinum(II) (CDDP) was determined by measuring succinate dehydrogenase (SD) activity in both electroporated and non-electroporated cells. In addition, intracellular concentrations of these anticancer agents were also measured. In the in vivo study, tumor-bearing C3H/He mice were treated with an intraperitoneal injection of anticancer agents followed by a local delivery of EP at the tumor site. Then, tumor growth rate (TGR) was determined and compared to that in the sham-treated control group, the EP-only group and the drug-only group. The in vitro study showed that, with electroporation, the cytotoxicity of BLM in electroporated cells was increased by as much as 95.7-fold compared to that of non-electroporated MBT-2 cells; CDDP showed only an increase of 1.8-fold and ADM showed no increase. After electroporation, the intracellular concentration of BLM, CDDP and ADM showed an increase of 120-, 1.7- and 0.8-fold, respectively. In electrochemotherapy for in vivo growing tumors, the potentiation of the antitumor effect was most prominent when combined with BLM, only slightly with CDDP, and totally absent with ADM. It is clear from in vitro and in vivo studies that, in a murine bladder tumor, the anticancer effect of BLM can be considerably potentiated by applying EP. Thus, BLM seems to be the most suitable anticancer agent for electrochemotherapy of bladder cancer.

Animals↗
PubMed2000

Psoas abscess complicating Crohn's disease: report of a case.

We describe herein the case of a psoas abscess complicating Crohn's disease, and present a review of the literature on this unusual disease entity. A 22-year-old Japanese man with a 5-year history of Crohn's ileocolitis presented with right lower abdominal and hip pain, and a diagnosis of right psoas abscess was subsequently made by abdominal computed tomography (CT). Following the administration of antibiotics and CT-guided percutaneous drainage of the abscess, the patient's symptoms temporarily improved; however, 2 weeks later, the abscess cavity was found to have extended around the periarticular tissue of the right hip joint. To prevent the development of septic arthritis of the hip joint, surgical drainage of the abscess cavity and ileocecal resection were immediately performed, after which the patient's condition greatly improved. The resected specimen showed Crohn's ileocolitis with an external fistula in the terminal ileum which was considered to have caused the psoas abscess. Since psoas abscess in Crohn's disease can result in serious complications such as septic arthritis of the hip joint if left untreated, aggressive treatment should be initiated without delay.

Adult↗
PubMed2000

[A case of cadaveric kidney transplantation from a heart-beating donor].

We experienced a case of cadaveric kidney transplantation from a heart-beating donor, a 23-year-old man who became brain dead after a traffic accident. The recipient, a 39-year-old man, had been receiving regular hemodialysis since 1990, was admitted to our hospital on June 14, 1999. The number of human lymphocyte antigen mismatches was 3. The left kidney of the donor was transplanted to the right iliac fossa of the recipient 6 hours 28 minutes after the start of in situ cooling of the kidney. For the purpose of immunosuppressive induction, tacrolimus, azathioprine, antilymphocyte globulin, methylpredonisolone and deoxyspergualin were administered. Immediate function was obtained, moreover, the serum creatinine level of the recipient was normalized without hemodialysis. The histopathological examination of the transplant kidney biopsied 1 hour after transplantation revealed little damage of renal tubules. Since no rejection episode was recognized, the patient was discharged on the 48th day after transplantation. This is the third case of cadaveric kidney transplantation from a heart-beating donor after enforcement of the law concerning organ transplantations in Japan.

Adult↗
PubMed2000

[Significance of interferon alpha therapy for advanced renal cell carcinoma. Fukushima Renal Cancer Study Group].

We ranked prognostic factors to retrospectively evaluate the clinical significance of interferon alpha (IFN-alpha) therapy in patients with Robson stage IVB renal cell carcinoma. A total of 44 Robson stage IVB renal cancer patients were divided into 2 groups, one with more than 6 months administration of IFN-alpha (3-7 times a week: group A) and another without any IFN-alpha administration. The distribution of these 2 groups was not randomized. In addition to IFN-alpha therapy, survival was analyzed with respect to performance status (PS), mass reductive nephrectomy, concomitant use of other cytotoxic therapies, the number of metastatic organs, growth type, site of metastasis and the period of diagnosis, using a multivariate method with Cox proportional hazards regression. The multivariate analysis showed administration of IFN-alpha to be the most significant factor influencing a good prognosis. Improved survival was also significantly correlated with slow growing type and good PS. Among group A, a significant favorable prognosis was obtained in patients with the responses of no change (NC), partial response (PR) and complete remission (CR) 6 months after initiating administration of IFN-alpha, as well as with good PS and a slow growing type carcinoma. We conclude that IFN-alpha therapy might improve the prognosis of patients with Robson stage IVB renal cell carcinoma, especially, in cases when a greater than NC response is obtained after 6 months administration of IFN-alpha.

Aged↗
PubMed1999

Transforming growth factor-beta1 inhibits the growth of primary adult rat hepatocyte cultures by increasing cAMP levels.

We investigated the mechanisms of transforming growth factor-beta1 (TGF-beta1) inhibition on transforming growth factor-alpha (TGF-alpha)-induced DNA synthesis and proliferation in primary cultures of adult rat hepatocytes. TGF-alpha (1.0 ng/ml) produced a 4.2-fold elevation of DNA synthesis during 3 h of culture and a 1. 2-fold increase in nucleus number (proliferation) during 4 h of culture. TGF-beta1 dose dependently inhibited the TGF-alpha-induced hepatocyte DNA synthesis and proliferation: half-maximal inhibition occurred at a TGF-beta1 concentration of 0.08 ng/ml. The inhibitory effects of 1.0 ng/ml TGF-beta1 were almost completely reversed by adenylate cyclase inhibitors, 2,4-dideoxyadenosine (10(-6) M), and somatostatin (3 x 10(-7) M), or by a specific inhibitor of protein kinase A, H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride; 10(-7) M). In addition, while TGF-alpha did not affect the basal cellular adenosine 3',5'-monophosphate (cAMP) levels, TGF-beta1 was found to produce dose-dependent increases in cellular cAMP levels. The cAMP-elevating effects of TGF-beta1 were also reversed by 2,4-dideoxyadenosine (10(-6) M), and somatostatin (3 x 10(-7) M), but not by H-89 (10(-7) M). The present results suggest that the specific mechanisms involved in the growth inhibitory effect of TGF-beta1 on TGF-alpha-induced hepatocyte DNA synthesis and proliferation are via stimulation of adenylate cyclase, which increases intracellular cAMP and subsequently activates protein kinase A.

Adrenergic Agonists↗
PubMed1999

Stimulation by transforming growth factor-alpha of DNA synthesis and proliferation of adult rat hepatocytes in primary cultures: modulation by alpha- and beta-adrenoceptor agonists.

We investigated the effects of transforming growth factor alpha (TGF-alpha) on DNA synthesis and proliferation in primary cultures of adult rat hepatocytes and examined the influence of alpha and beta adrenoceptor agonists on the TGF-alpha-induced responses. TGF-alpha (1.0 ng/ml) produced a 4.1-fold elevation of DNA synthesis during 3 h of culture and a 1.2-fold increase in the nucleus number (proliferation) during 4 h of culture at a cell density of 3.3 x 10(4) cells/cm(2). The TGF-alpha-induced hepatocyte DNA synthesis and proliferation were dose-dependent at EC(50) values of 0.36 ng/ml and 0.45 ng/ml, respectively. Hepatocyte DNA synthesis and proliferation induced by 1.0 ng/ml TGF-alpha did not reduce even at higher initial plating densities (5.0 x 10(4) and 1.0 x 10(5) cells/cm(2)). Increasing concentrations of the beta(2) adrenoceptor agonist metaproterenol (10(-7)-10(-6) M) markedly reduced the proliferative effects of TGF-alpha, whereas those of the alpha(2) adrenoceptor agonist 5-bromo-6-[2-imidazolin-2-yl-amino]-quinoxaline (UK-14304; 10(-6)-10(-5) M) and the alpha(1) adrenoceptor agonist phenylephrine (10(-7)-10(-6) M) significantly potentiated the TGF-alpha action. The proliferative effects of TGF-alpha (1.0 ng/ml) were not affected significantly by a monoclonal antiepidermal growth factor receptor antibody (1-100 ng/ml) and were almost completely blocked by specific inhibitors of signal transducers such as genistein (10(-5) M), 1-6[[17beta-3methoxyestra-1,3, 5(10)-trien-17-yl]amino]hexyl]-1H-pyrrol2,5-dione (U-73122; 0(-5) M), wortmannin (5 x 10(-7) M), sphingosine (5 x 10(-6) M), 2'-amino-3'-methoxyflavone (PD98059; 5 x 10(-5) M), and rapamycin (10 ng/ml). These results suggest that among the elements that link signals of cell surface receptor to the nucleus, the proliferative action of TGF-alpha is mediated, at least, by tyrosine kinase, phospholipase C, phosphatidylinositol 3-kinase, protein kinase C, mitogen-activated protein kinase kinase, and ribosomal protein p70 S6 kinase.

Adrenergic Antagonists↗
PubMed1998

Effects of insulin-like growth factor I and II on DNA synthesis and proliferation in primary cultures of adult rat hepatocytes.

We compared the effects of insulin-like growth factor I (IGF-I) and II (IGF-II) on DNA synthesis and proliferation and investigated various signal transduction mechanisms involved in insulin-like growth factor-induced mitogenesis in primary cultures of adult rat hepatocytes. IGF-I stimulated hepatocyte DNA synthesis and proliferation with an EC50 of 75 ng/ml within 4 h of culture. These effects were sensitive to the IGF-I concentration and cell density. Hepatocyte proliferation induced by IGF-I was potentiated by metaproterenol (10(-6) M) as well as by 8-bromo-cAMP, phorbol 12-myristate 13-acetate (PMA; 10(-8) M) and was inhibited by U-73122 (1-(-[[17beta-3-methoxyestra-1,3,5(10)-triene-17-yl]amino]hexyl]-+ ++1Hpyrrol-2,5-dione)), genistein, wortmannin, PD98059 (2'-amino-3'-methoxyflavone) and rapamycin. The IGF-I effect was independent of pertussis toxin (100 ng/ml). IGF-II also dose dependently stimulated hepatocyte DNA synthesis and proliferation with an EC50 of 0.75 ng/ml within 4 h of culture. However, these effects were not dependent on the initial plating density. The stimulatory effects of IGF-II were potentiated by UK-14304 (5-bromo-6-[2-imidazolin-2-ylamino]-quinoxaline) (10(-5) M) and inhibited by phenylephrine, PMA, metaproterenol, 8-bromo-cAMP, PD98059, rapamycin, and pertussis toxin. The IGF-II effects were not affected by genistein, U-73122, and wortmannin. These results suggest that IGF-I and IGF-II rapidly stimulate the DNA synthesis and proliferation of adult rat hepatocytes by separate mechanisms.

Animals↗
PubMed1998

Expression of alpha2- and beta2-adrenergic responses by hepatocyte growth factor and platelet-derived growth factor in primary cultures of adult rat hepatocytes.

We investigated the effects of hepatocyte growth factor (HGF) and platelet-derived growth factor (PDGF) on the expression of alpha2- and beta2-adrenergic responses in primary cultures of adult rat hepatocytes. HGF (1 and 5 ng/ml) rapidly stimulated the expression of beta2-adrenergic responses and significantly increased alpha2-adrenergic responses with a maximal response at 21 h. The stimulatory effects of HGF were reduced dependent on the initial plating density and were completely blocked by cycloheximide (5 microM). On the other hand, PDGF (10 ng/ml) significantly increased the beta2-adrenergic response, but only slightly increased the alpha2-adrenergic responses. Expression of the alpha2- and beta2-adrenergic responses by PDGF was independent of the initial plating density. The expression of these responses was blocked by cycloheximide (5 microM). Northern blot analysis of the hepatocyte mRNA showed increased expression induced by the HGF and PDGF of the both alpha2- and beta2-adrenergic receptor mRNA, and this expression was inhibited by actinomycin D (5 ng/ml). These results indicate that the expression of alpha2- and beta2-adrenergic responses produced by these two growth factors is regulated differently by the cell density of the primary cultures. The results suggest that the expression of alpha2- and beta2-adrenergic responses is mediated through increased synthesis of these receptor proteins.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1998

[Inhibitory effects of shimotsu-to, a traditional Chinese herbal prescription, on ultraviolet radiation-induced cell damage and prostaglandin E2 release in cultured Swiss 3T3 cells].

We have investigated the effects of Shimotsu-to, a traditional Chinese herbal prescription (Kampo medicine), on ultraviolet (UV) radiation-induced cell damage and prostaglandin E2 (PGE2) release in cultured Swiss 3T3 cells to examine the anti-inflammatory mechanism of Shimotsu-to. Short-term UV irradiation significantly induced cell damage and stimulated PGE2 release in Swiss 3T3 cells cultured for 4 h. The UV-radiation-induced cell damage and the stimulation of PGE2 release were significantly suppressed by the treatment with Shimotsu-to. Among the single crude drug components of Shimotsu-to, Rehmanniae Radix showed significant protective effects against UV-radiation-induced cell damage and PGE2 release. Other synthetic anti-inflammatory agents, such as dexamethasone, dipotassium glycyrrhizinate and allantoin also protected against UV-induced cell damage and inhibited PGE2 release in cultured Swiss 3T3 cells. These results suggest that the anti-inflammatory mechanism of Shimotsu-to against UV-irradiated erythema (acute skin inflammation) in guinea pigs in vivo may be mediated by the inhibition of PGE2 release from cutaneous target cells.

3T3 Cells↗
PubMed1998

Proliferation of adult rat hepatocytes in primary cultures induced by platelet-derived growth factor is potentiated by phenylephrine.

We investigated whether or not proliferation of adult rat hepatocytes induced by platelet-derived growth factor (PDGF) is affected by alpha1-adrenoceptor agonists such as phenylephrine during the early and late phases of primary culture. Adult rat hepatocytes underwent significant DNA synthesis after culture with 10 ng/ml of PDGF for 2 hr at a low cell density (3.3 x 10(4) cells/cm2). Under these culture conditions, the number of nuclei increased significantly during the 3.5-hr culture period. Hepatocyte DNA synthesis and proliferation induced by 10 ng/ml of PDGF decreased slightly as a result of increasing the initial plating density. An alpha1-adrenoceptor agonist, phenylephrine (10(-6) and 10(-5) M), alone did not affect hepatocyte DNA synthesis and proliferation, but markedly potentiated PDGF-induced hepatocyte DNA synthesis and proliferation. The phenylephrine effect was mimicked by phorbol myristate acetate (10(-7) M), but not by ionomycin (10(-5) M). The mitogenic effects of PDGF were almost completely blocked by treating hepatocytes with genistein (5 x 10(-6) M), U-73122 (3 x 10(-6) M), sphingosine (10(-5) M), wortmannin (10(-7) M) and rapamycin (10 ng/ml). These results demonstrate that PDGF can induce the proliferation of adult rat hepatocytes rapidly in primary culture, regardless of the initial plating density. The present results also suggest that following stimulation with PDGF, activation of tyrosine kinase, phospholipase C, phosphatidylinositol 3-kinase, protein kinase C (PKC) and p70 ribosomal protein S6 kinase is essential for the proliferation of adult rat hepatocytes. The co-mitogenic effects of phenylephrine may involve PKC activation.

Adrenergic alpha-Antagonists↗
PubMed1998

[A case of multiple sclerosis with initial symptoms of narcolepsy].

We reported a 13-year-old boy diagnosed as multiple sclerosis associated with narcolepsy. He had suffered from retrobulbar optic neuritis at the age of 11 years which was improved gradually by prednisolone. Four months later he was admitted because of excessive somnolence. The diagnosis of narcolepsy was made based on hypnagogic hallucination, sleep paralysis, changes of personality and the sleep onset sREM (SOREM). The elevation of anti-measles antibody and a positive oligoclonal band in CSF, low density areas in the bilateral internal capsule on CT scan, and high signal areas in the same region on T2-weighted MRI confirmed the diagnosis of multiple sclerosis. An abnormal arousal response occurred occasionally in sleep stage 2 and 4, which started with electrical silence followed by a period with irregular high voltage slow waves and repetitive focal spike train. Those clinical symptoms and abnormalities of biochemical and electrophysiological studies normalized after treatment with prednisolone. However, abnormalities on MRI showed no improvement even after long term administration of prednisolone (2.5 mg/day).

Adolescent↗
PubMed1998

[Management of difficult airway during induction of anesthesia in a patient with Hallermann-Streiff syndrome].

An 18-year-old female with Hallermann-Streiff syndrome underwent the fixation of prolapsus recti. She had significant microgenia, mental retardation and pharyngeal airway stenosis. During induction of anesthesia with halothane and nitrous oxide, severe upper airway obstruction and respiratory depression occurred. The mask ventilation with jaw lift maneuver was impossible. Lowering anesthetic level restored her spontaneous breathing and airway patency. Although the direct laryngoscopic view under light anesthesia with halothane was limited to the epiglottic tip, blind orotracheal intubation using stylet was accomplish after several attempts. At the end of anesthesia, the tracheal tube was extubated after the patient had become fully awake and had recovered completely from neuromuscular blockade monitored by electromyography.

Adolescent↗
PubMed1997

Proliferation of adult rat hepatocytes in primary culture induced by insulin is potentiated by cAMP-elevating agents.

We investigated whether or not insulin and cAMP-elevating agents induce the proliferation of adult rat hepatocytes during the early and late phases of primary culture. Adult rat hepatocytes synthesized a significant amount of DNA when cultured in the presence of 10(-7) M insulin for 3 h. Under these conditions, the number of nuclei increased within 4 h. Hepatocyte DNA synthesis and proliferation were not essentially affected by the initial plating densities. Other cAMP-elevating agents, such as glucagon, forskolin and dibutyryl cAMP, as well as beta-adrenoceptor agonists (i.e., metaproterenol and isoproterenol) alone had no effect on either hepatocyte DNA synthesis or proliferation in primary culture. In contrast, these agents potentiated both processes at concentrations as low as 10(-7) M when cultured in combination with 10(-7) M insulin. The stimulatory effects of beta-adrenoceptor agonists and other cAMP-elevating agents were significantly blocked by the cAMP-dependent protein kinase inhibitor, H-89 (N-[2-(p-(bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride; 10(-7) M). The mitogenic effect of insulin upon hepatocytes was almost completely suppressed by genistein (5 x 10(-6) M), wortmannin (10(-7) M) and by rapamycin (10 ng/ml). These results show that insulin rapidly induced the proliferation of adult rat hepatocytes in primary culture. The mitogenic effects of insulin were potentiated by beta-adrenoceptor agonists and cAMP-elevating agents. The effects of beta-adrenoceptor agonists and cAMP-elevating agents may be mediated through cAMP-dependent protein kinase. In addition, the activation of receptor tyrosine kinase, phosphoinositide 3-kinase and p70 ribosomal protein S6 kinase may be involved in the insulin signal transduction pathway.

1-Methyl-3-isobutylxanthine↗
PubMed1997

Density-dependent proliferation of adult rat hepatocytes in primary culture induced by epidermal growth factor is potentiated by cAMP-elevating agents.

We investigated whether or not epidermal growth factor (EGF) and cAMP-elevating agents induce the proliferation of adult rat hepatocytes during the early (4 h after adding EGF) and late phases (21 h after adding EGF) of primary cultures. Adult rat hepatocytes did not significantly proliferate after culture with 20 ng/ml EGF for 4 h at a density of 1 X 10(5) cells/cm2. In contrast, when the density was decreased by about one-third to 3.3 X 10(4) cells/cm2, the number of nuclei increased about 1.2-fold after culture with 10-20 ng/ml EGF for 4 h. Under these culture conditions, DNA synthesis began within 2-4 h of exposure to 20 ng/ml of EGF, although at the high cell density, DNA was not synthesized during this period. The beta-adrenoceptor agonists, metaproterenol and isoproterenol, and other cAMP-elevating agents, such as glucagon, forskolin, and dibutyryl cAMP, potentiated both hepatocyte DNA synthesis and proliferation about 1.4-fold when cultured in combination with 20 ng/ml EGF. The stimulatory effects of metaproterenol and other cAMP-elevating agents were specifically blocked by the cAMP-dependent protein kinase inhibitor, H-89 (10(-7) M). The effect of EGF was almost completely suppressed by genistein (5 X 10(-6) M) and rapamycin (10 ng/ml), but it was unaffected by wortmannin (10(-7) M). These results demonstrate that mature rat hepatocytes can proliferate very rapidly in low-density cultures with EGF, the effects of which were potentiated by beta-adrenoceptor agonists and cAMP-elevating agents. In addition, the activation of receptor tyrosine kinase and p70 ribosomal protein S6 kinase may be involved in EGF-induced hepatocyte DNA synthesis and proliferation.

Adrenergic beta-Agonists↗
PubMed1997

[Neoadjuvant intra-arterial chemotherapy based on chemosensitivity tests for locally invasive bladder cancer].

We investigated the clinical usefulness of individualization of chemotherapeutic regimen in neoadjuvant intra-arterial chemotherapy for locally invasive bladder cancer. Anticancer drugs were selected according to the results of an in vitro chemosensitivity test (collagen matrix assay or succinic dehydrogenase inhibition test). Nine patients with locally invasive bladder cancer received 1 to 4 courses of neoadjuvant intra-arterial chemotherapy, followed by radical cystectomy. Histopathological responses in the cystectomized specimens were grade 3 in 3 cases, grade 2 in 2, grade 1b in 2 and no response in 2. Pathologically, a complete response and downstaging were observed in 3 and 4 cases, respectively. Seven of the 9 patients were alive no evidence of disease with a mean follow-up period of 38.9 months, whereas 2 patients died of metastasis within 2 years. Six of the 7 patients who showed a complete response or down staging have been free of recurrence. These findings suggest that our chemotherapeutic strategy may improve the prognosis for locally invasive bladder cancer.

Aged↗
PubMed1997

Proliferation of adult rat hepatocytes by hepatocyte growth factor is potentiated by both phenylephrine and metaproterenol.

We investigated whether or not beta and alpha adrenergic agonists could affect proliferation of adult rat hepatocytes induced by hepatocyte growth factor (HGF) during the early and late phases of primary culture. Adult rat hepatocytes underwent significant DNA synthesis after culture with 5 ng/ml HGF for 3 h at a low cell density (3.3 x 10(4) cells/cm2). Under these culture conditions, the number of nuclei increased significantly during a subsequent 4-h culture period. Hepatocyte DNA synthesis and proliferation induced by 5 ng/ml HGF was reduced at high cell densities near confluence. A beta adrenergic agonist, metaproterenol (10(-7) M), and dibutyryl cAMP significantly potentiated hepatocyte DNA synthesis and proliferation at a concentration as low as 10(-7) M when cultured in combination with 5 ng/ml HGF. Similarly, an alpha-1 adrenergic agonist, phenylephrine (10(-6)-10(-4) M) markedly potentiated HGF-induced hepatocyte DNA synthesis and proliferation. The phenylephrine effect was mimicked by a phorbol ester (10(-6) M), but not by ionomycin (10(-6) M). The mitogenic effects of HGF were almost completely blocked by simultaneous treatment of hepatocytes with genistein (5 x 10(-6) M), U-73122 (10(-6) M), wortmannin (10(-7) M), sphingosine (3 x 10(-6) M) and rapamycin (10 ng/ml). These results demonstrate that HGF can rapidly induce proliferation of adult rat hepatocytes in primary culture. However, this effect is dependent on the initial plating density. The co-mitogenic effects of metaproterenol and phenylephrine may involve both protein kinase A and protein kinase C activation, respectively. The results also suggest that following stimulation with HGF, activation of tyrosine kinase, phosphatidylinositol 3-kinase, phospholipase C and p70 ribosomal protein S6 kinase is essential for hepatocyte proliferation.

Adrenergic beta-Antagonists↗