Biomedical subjects

K Akiyoshi

Publications and source records attributed to K Akiyoshi.

At least 19 recordsLinked to original sources

PubMed2004

Single molecular mechanics of a cholesterol-bearing pullulan nanogel at the hydrophobic interfaces.

The study of nanogel (hydrogel nanoparticle) has intensified in the last decade due to the enormous potential applications in biomimetics, biosensors, artificial muscles and drug delivery (or release) systems. Cholesterol-bearing pullulan (CHP) is composed of hydrophilic pullulan backbone and partly substituted hydrophobic cholesterol, and is capable of forming a stable hydrogel nanoparticle in aqueous solution due to the self-assembly of hydrophobic cholesterol moieties. The conformation of CHP changes dramatically at the hydrophobic interfaces. In order to understand the interfacial responses of CHP, the interaction forces of CHP nanogels to the hydrophobic HOPG (highly orientated pyrolytic graphite) or carbon-coated surfaces were measured using atomic force microscope. The freely jointed china model for CHP molecular elasticity was applied to the force-extension curves and debonding force-pull-off distance in order to estimate the contour lengths and the segment lengths of the CHP molecules. The segment length of CHP chains in aqueous solution was estimated 0.32+/-0.19 nm showing a very flexible chain. From our analysis of the dynamic force measurements, the debonding forces were shown to depend on the applied loading forces. The zero kinetic off-rate K(off)(0) and the transition state x(b) were estimated to be 1.1 x 10(-3)s(-1) and 2.9A, respectively.

Biocompatible Materials↗

PubMed2001

Outcome of acute lymphoblastic leukemia in children with AL90 regimen: impact of response to treatment and sex difference on prognostic factors.

BACKGROUND: In our previous studies, the outcome of high-risk ALL was still poor. In the present study, all children with ALL were classified into three groups and treated with a new regimen (AL90). PATIENTS AND METHODS: Between 1990 and 1996, 220 children with ALL, treated with the AL90 regimen, were classified into three risk groups: low, intermediate, and high: LR, IR, and HR, respectively. The protocol consisted of three- to five-drug induction, consolidation with intermediate-dose methotrexate and/or cytarabine, mercaptopurine and cyclophosphamide, four-drug intensification, and sequential maintenance therapies. Only intrathecal chemotherapy was used for CNS prophylaxis in the LR group, whereas cranial irradiation was added for the IR and HR groups. RESULTS: The number of eligible patients was 91: LR group, 71: IR group, and 58: HR group. Complete remission (CR) was obtained in > 98% of the LR and IR groups, while only 88% achieved CR in the HR group. The 5-year event-free survival (EFS) rate was 67.4% in all patients: 70.4% in the LR group, 71.7% in the IR group, and 57.5% in the HR group. With respect to the previous study, EFS in the HR group who showed positive residual leukemia at 14 days was improved, whereas EFS in boys versus girls was significantly lower (48.8% : 85.7%, P = 0.02). CONCLUSIONS: In high-risk ALL, the rate of induction failure was high and boys had a worse outcome, calling for improvements in induction therapy and a specific approach for boys.

Adolescent↗

PubMed2001

Long-term outcome of treatment with protocols AL841, AL851, and ALHR88 in children with acute lymphoblastic leukemia: results obtained by the Kyushu-Yamaguchi Children's Cancer Study Group.

We analyzed the long-term outcome and late effects of treatment in 187 patients with childhood acute lymphoblastic leukemia (ALL) diagnosed between 1984 and 1990. Overall survival and event-free survival rates were 68.2% +/- 3.7% and 63.2% +/- 3.6% at 15 years, respectively. Of 55 patients who relapsed after achieving the first complete remission (CR), only 17.4% were rescued by salvage therapy. The advantage of stem cell transplantation over chemotherapy was observed only in those patients with bone marrow relapse during therapy. The SD for score height in patients maintaining the first CR significantly decreased at the time of final follow-up compared with that at diagnosis: 0.059 to -0.800 (P < .0001). The decrease was remarkable in patients younger than 5 years at diagnosis. Other late effects included mild liver dysfunction in 18% and hepatitis C virus infection in 9%. Congestive heart failure was observed in only 2.9% of patients despite the high cumulative dose of daunorubicin (450 mg/m2). Although the survival rates of patients on our protocols were comparable to those of other study groups, some modification, including reduction in dose of cranial irradiation and/or anticancer drugs, should be considered to reduce late adverse effects in survivors of childhood ALL.

Adolescent↗

PubMed2001

Effects of olprinone, a new phosphodiesterase inhibitor, on gastric intramucosal acidosis and systemic inflammatory responses following hypothermic cardiopulmonary bypass.

BACKGROUND: Phosphodiesterase (PDE) III inhibitors have both an inotropic and a peripheral vasodilatory effect, and also inhibit the activation of macrophages. Thus a newly developed PDE III inhibitor, olprinone, could modify gastric intramucosal pH (pHi), systemic oxygen consumption, and systemic inflammatory responses in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). METHODS: We studied 23 patients. In 15 patients, olprinone (0.1 or 0.2 microg x kg(-1) x min(-1)) was administered from the commencement of CPB until their admission to the ICU. The other 8 patients received placebo. The pHi and regional CO2 tension (PrCO2) were assessed by a capnometric air tonometry. Systemic inflammatory responses were evaluated by serum interleukin-6 (IL-6), IL-10, and leucocyte counts. RESULTS: The pHi and PCO2-gap, the difference between PrCO2 and arterial CO2 tension (PaCO2), showed a transient decrease and an increase after CPB, respectively. Although olprinone did not affect pHi, olprinone at 0.2 microg x kg(-1) x min(-1) significantly lessened post-CPB increase in PCO2-gap. Olprinone at 0.2 microg x kg(-1) x min(-1) significantly increased IL-10 and reduced the extent of leucocytosis, while it did not affect IL-6 levels. At the same dosage, olprinone also lessened the surge in systemic oxygen uptake index (VO2) and augmented the increase in mixed oxygen saturation (SvO2) both of which occurred after CPB. At 0.1 microg x kg(-1) x min(-1), however, olprinone did not show any significant effect. CONCLUSION: Our results suggest that olprinone at 0.2 microg x kg(-1) x min(-1) suppresses gastric intramucosal acidosis and systemic inflammation following CPB.

Acidosis↗

PubMed2001

Effect of low-dose milrinone on gastric intramucosal pH and systemic inflammation after hypothermic cardiopulmonary bypass.

OBJECTIVE: To investigate the usefulness of low-dose milrinone on gastric intramucosal pH (pHi) and systemic inflammation in patients undergoing hypothermic cardiopulmonary bypass (CPB). DESIGN: Prospective randomized study. SETTING: University hospital. PARTICIPANTS: Twenty patients scheduled for cardiac surgery. INTERVENTIONS: Ten patients were administered a low dose of milrinone, 0.25 microg/kg/min, from the initiation of CPB to 1 hour after admission to the intensive care unit. The other patients were administered saline. Supplemental inotropes and intravenous fluid were given to obtain adequate mean arterial blood pressure and pulmonary artery occlusion pressure. MEASUREMENTS AND RESULTS: Gastric pHi and carbon dioxide pressure (PCO2) were assessed by capnometric air tonometry. The difference between PCO2 and arterial carbon dioxide pressure (PaCO2), PCO2-gap, was also examined. Systemic inflammatory responses were evaluated by serum interleukin-6 and leukocyte counts. Hemodynamics, oxygen delivery index, and oxygen uptake index were monitored with catheters in the radial and pulmonary arteries (thermodilution). The hepatic venous blood flow and left ventricular flow were measured using transesophageal echocardiography. Milrinone prevented gastric intramucosal acidosis, detected as a decrease in pHi or an increase in PCO2-gap, without affecting hepatic venous blood flow. Increases in interleukin-6, leukocyte count, and oxygen uptake index, all of which developed after CPB, were significantly less in the milrinone group than in the control group. CONCLUSION: These results suggest that in patients undergoing hypothermic CPB, supplemental low-dose milrinone prevents gastric intramucosal acidosis and increases in some markers of systemic inflammation.

Body Temperature↗

PubMed2001

Reduction of carotid artery blood flow in pediatric patients with syncope: evaluation with head-up tilt test.

We investigated the effect of postural changes on cerebral circulation by measuring carotid artery blood flow (CABF) in the supine position and during head-up tilt (HUT) test using a Doppler flow meter. Subjects included 10 patients with neurally mediated syncope, 10 patients with orthostatic intolerance, 8 with epilepsy, aged between 8 to 24 years (mean +/- SD, 13.9 +/- 4.1 years). The test caused pallor and dizziness in 16 patients (symptomatic), while no symptoms were recognized in the other 12 patients (asymptomatic). Significant reductions in the mean CABF (Fm), maximum CABF (Fs) and minimum CABF (Fd), components of the CABF waveform, were noticed during HUT compared to before HUT (supine), and these reductions in symptomatic patients were more severe than those in asymptomatic patients (Fm: - 2.8 +/- 2.0 SD vs - 0.7 +/- 1.4 SD; Fs: - 2.7 +/- 1.5 SD vs - 0.9 +/- 1.3 SD; Fd: - 4.5 +/- 2.8 SD vs - 2.2 +/- 2.1 SD). Reductions in Fm, Fs and Fd in the symptomatic patients during HUT lasted longer than those of the asymptomatic patients, being statistically significant for Fm and Fs (Fm: p < 0.01; Fs: p < 0.05). The criteria during HUT for distinguishing neurally mediated syncope (NMS) from others was Fs: < - 4 SD and Fd: < - 5 SD. Our data suggest that reduction of CABF should be carefully evaluated for the diagnosis of neurally mediated syncope in pediatric patients. Such a reduction might be an essential mechanism of syncopal attacks.

Adolescent↗

PubMed2001

Effect of coronary artery bypass grafting with gastroepiploic artery on gastric intramucosal pH and systemic inflammation.

BACKGROUND: The purpose of this study was to investigate the effect of coronary arterial bypass grafting (CABG) with gastroepiploic artery (GEA) on gastric intramucosal pH and systemic inflammation. METHODS DESIGN: retrospective study. SETTING: University hospital. PARTICIPANTS: 22 patients underwent CABG. INVESTIGATIONS: the GEA group (n=13) received CABG with the GEA graft. The non-GEA group (n=9) received conventional CABG without the GEA graft. MEASUREMENTS: gastric intramucosal pH (pHi) and carbon dioxide tension (PrCO(2)) were assessed by capnometric air tonometry. The difference between PrCO(2) and PaCO(2), PCO(2)-gap, was also determined. Systemic inflammatory responses were evaluated by serum interleukin-6 (IL-6) and leucocyte counts. Hemodynamics, oxygen delivery index (DO(2)I) and uptake index (VO(2)I) were monitored with catheters in the radial and pulmonary arteries (thermodilution). RESULTS: The duration of aortic cross-clamping and cardiopulmonary bypass was similar in both groups. Both groups did not show any significant difference in gastric pHi, PCO(2)-gap, systemic inflammation and hemodynamics. CONCLUSIONS: Our findings suggest that CABG using the GEA graft does not disturb gastric mucosal perfusion, and that laparotomy for the GEA graft does not aggravate systemic oxygen demand-supply imbalance or systemic inflammatory responses induced by hypothermic CPB. CABG with the GEA graft does not seem to pose an additional risk and is a safe technique compared with conventional CABG with regard to pHi and systemic inflammation.

Aged↗

PubMed2000

Capillary hemangioma of the liver with Kasabach-Merritt syndrome in a neonate: report of a case.

Hepatic hemangiomas are benign tumors, and therefore minimally invasive treatment such as irradiation or steroid therapy is often recommended. However, in patients who have a hemangioma complicated by Kasabach-Merritt syndrome, surgical intervention should also be considered because of its confirmative therapeutic effect. We present herein the case of a 32-day-old male infant in whom a huge hepatic hemangioma associated with Kasabach-Merritt syndrome was treated by surgical intervention together with strong antidisseminated intravascular coagulation therapy.

Disseminated Intravascular Coagulation↗

PubMed2000

Development of a cancer vaccine: peptides, proteins, and DNA.

Genetic changes leading to protooncogene activation qualitatively and/or quantitatively alter their gene products and are exclusively or largely restricted to transforming cells and their precursors. The overexpression of HER2 is among those changes and is often detected in adenocarcinomas such as breast, ovarian, lung, and gastric cancer. This provides a rationale for exploring the possibility that HER2 is a target of host immune responses against cancer cells. We have recently demonstrated that HER2 can be a target for tumor-rejecting immune responses against syngeneic murine HER2+ tumor cells. We defined two different peptides, HER2p63-71 and HER2p780-788, with a Kd anchor motif that can induce CD8+ cytotoxic T lymphocytes (CTLs). The growth of HER2+ syngeneic tumors was suppressed in mice immunized with HER2p63-71 or p780-788. Since murine Kd and human HLA-A24 share a similar anchor motif for peptides, HER2p63 71 and HER2p780-788 were examined for induction of CTLs in HLA-A24+ individuals. CD8+ CTL clones specific for these peptides were established and they lysed HER2+ tumor cells in a human leukocyte antigen (HLA)-A24-restricted manner. To elicit specific CD8+ T cell immune responses against cancer, the development of efficient devices to deliver tumor antigen peptides to the major histocompatibility complex (MHC) class I pathway constitutes a central issue. We have developed a novel formula of hydrophobized polysaccharide nanoparticles which can deliver a HER2 oncoprotein containing an epitope peptide to the MHC class I pathway. We designed a simple protein delivery system: cholesteryl group-bearing polysaccharides, mannan or pullulan (CHM or CHP, respectively), complexed with the truncated HER2 protein containing the 147 N-terminal amino acids. These complexes were able to induce CD8+ CTLs against HER2+ tumors. CTLs were MHC class I restricted and specifically recognized HER2p63-71, a part of a truncated HER2 protein used as an immunogen. The complete rejection of tumors also occurred when CHM-HER2 was applied early after tumor implantation. In the effector phase of in vivo tumor rejection, CD8+ T cells played a major role. The results suggest that this unique hydrophobized polysaccharide may help soluble proteins to induce cellular immunity. Such a novel vaccine may be of potential benefit in cancer prevention and cancer therapy.

Animals↗

PubMed2000

Changes in left ventricular end-diastolic area, end-systolic wall stress, and fractional area change during anesthetic induction with propofol or thiamylal.

PURPOSE: To elucidate the mechanisms of the more profound hypotensive effects of propofol relative to thiamylal, we monitored changes in left ventricular (LV) preload, afterload, and contractility during the course of anesthetic induction with propofol and thiamylal. METHODS: Thirty-two patients (ASA I) were randomly assigned into two groups and injected with propofol (2 mg.kg(-1)) or thiamylal (4 mg.kg(-1)) as anesthetic induction agents. Transthoracic echocardiography (TTE) was used to assess LV performance before and during induction by the two anesthetics. The LV end-diastolic area (EDA) and LV end-systolic wall stress (ESWS) were used as indices of LV preload and LV afterload, respectively, while LV contractility was assessed by the fractional area change (FAC). RESULTS: Both propofol and thiamylal significantly reduced EDA and ESWS without significant change in FAC. Propofol-induced reductions in EDA and ESWS were significantly greater than those of thiamylal. CONCLUSION: The more profound hypotension observed during induction of anesthesia with propofol is due to the greater decrease in preload and afterload than with thiamylal, but not to a decrease in LV contractility.

Clinical Trial↗

PubMed2000

Ganglioside patterns in neuroepithelial tumors of childhood.

To elucidate a relationship between neuronal anaplasia, tumor proliferation, and ganglioside contents, we quantified gangliosides by HPTLC in tumors of neuroepithelial tissues at different grade, i. e. peripheral primitive neuroectodermal tumor (PPNET, grade IV), ependymoma (EPEN, grade III), neuroblastoma (NB, grade IV), and dysembryoplastic neuroepithelial tumor (DNT, grade I). PPNET, the most undifferentiated tumor examined had lowest concentration of total lipid-bound sialic acid. GM3 was the major ganglioside in all undifferentiated tumors (46-72.7% of total lipid-bound sialic acid). GD3 was an another component in PPNET and EPEN (7.2-17.3%). Concentration of a complex gangliosides GM1 was decreased in all tumor tissues and those of GT1a, GD1b and GT1b were decreased in tumors of high grade. The results suggest that the composition of gangliosides could be of considerable value in refining the classification of neuroepithelial tumors in infancy and childhood.

Adolescent↗

PubMed2000

Pulmonary lipiodol embolism during transcatheter arterial chemoembolization for hepatoblastoma under general anaesthesia.

We present a case of pulmonary embolism that occurred during the injection of lipiodol during transcatheter arterial chemoembolization under general anaesthesia. A 7-year-old child suffering from a large hepatoblastoma was admitted for arterial chemoembolization and carcinostatic administration. Pulmonary embolism due to lipiodol during arterial chemoembolization was evident by a sudden fall in oxyhaemoglobin saturation from 100 to 90%. This was associated with a spread of lipiodol into both lungs, particularly the middle lung zones and detected by chest fluoroscopy. Arterial blood gases returned to normal values 1 day later but pulmonary infiltration persisted for 7 days before final clearance. Pulmonary embolism caused by lipiodol during arterial chemoembolization is infrequent, but such a complication could prove fatal. Understanding the risk of pulmonary embolism in patients receiving lipiodol, during and after arterial chemoembolization, and late onset pulmonary injury is important and a close follow-up for several days after arterial chemoembolization is advisable.

Antibiotics, Antineoplastic↗

PubMed1999

Inhibitory effect of TS-962 on the formation of early atherosclerotic lesions in high fat-fed hyperlipidemic hamsters.

The hypocholesterolemic and anti-atherosclerotic effect of TS-962, a specific ACAT inhibitor, was investigated in a hamster model fed a high fat diet containing 10% coconut oil and 0.05% cholesterol. Lipid accumulated atherosclerotic lesions were detected by using oil red O staining in the lesion-prone aortic arch. A high dose, estimated to be 15 mg/kg, of TS-962 decreased serum cholesterol to normal levels with reduction of liver cholesterol contents below normal levels, and as a consequence, entirely inhibited the lipid accumulation in the aortic arch. Furthermore, a low dose, estimated to be 1.5 mg/kg, of TS-962 remarkably inhibited aortic lipid accumulation by 73% compared with the control group, without changing either serum cholesterol level or liver cholesterol content. These findings suggest that TS-962 is effective in the primary prevention of atherosclerosis by directly suppressing the formation of foam cells in arteries.

Acetamides↗

PubMed1999

Two-dimensional autoregressive analysis of carotid artery blood flow waveform in children with isolated atrial septal defect.

BACKGROUND: The aim of the present study was to analyze the carotid artery blood flow waveform, using a two-dimensional autoregressive modeling approach and component analysis, and to determine the relation between cardiac contractility, peripheral and cerebral circulation and characteristic values of component activities of carotid artery blood flow waveform in patients with atrial septal defect (ASD), with or without congestive heart failure. METHODS AND RESULTS: We analyzed the carotid artery blood flow waveform of nine patients with ASD and 35 normal controls using a two-dimensional autoregressive modeling approach. The component of impulse response was divided into six groups according to the damping frequency: (i) group I, 0 Hz; (ii) group II, 1-5 Hz; (iii) group III, 5-8 Hz; (iv) group IV, 8-13 Hz; (v) group V, 13-17 Hz and (vi) group VI, > 17 Hz. The decrease of impulse response power-density in patients of groups I, II, III and IV and the prolongation of damping time for patients in groups I and II were particularly noticeable in two ASD patients, whose pulmonary to systemic blood flow ratio was more than 2.7 and whose left ventricular stroke volume was less than 33.1 mL/m2. The power-density of groups I and II varied with cardiac contractility and the power-density of groups III and IV varied with cerebral circulation. In contrast, the damping time of groups I and II changed with the reflection velocity from the position of arterial reflection against blood flow from left ventricle. CONCLUSIONS: These results may be influenced by the decrease in left ventricular stroke volume and velocity in arterial reflection.

Blood Circulation↗

PubMed1999

Bone marrow-derived dendritic cells incorporate and process hydrophobized polysaccharide/oncoprotein complex as antigen presenting cells.

We have previously shown that a novel hydrophobized polysaccharide/oncoprotein complex vaccine can induce immune responses against the HER2/neu/c-erbB2 (HER2) expressing tumors. Bone marrow-derived dendritic cells (DCs), as antigen presenting cells (APCs), are the first candidates for presentation of tumor antigens. The aim of this study was to see whether DCs are able to elicit antigen specific host immune responses by stimulating the proliferation of T cells after exposure to cholesteryl group bearing pullulan (CHP) and HER2 protein complex. Vaccination by CHP-HER2 complex was as effective as cholesteryl group bearing mannan (CHM) and HER2 complex on which we reported previously. Immunization of mice with HER2 expressing CMS17HE tumor cells generated both CD4+ T cells and CD8+ T cells reactive with CHP-HER2 complex pretreated DCs. In addition, immunization with either CHP-HER2 complex or HER2 protein alone could also generate both CD4+ T cells and CD8+ T cells specifically reactive with CHP-HER2 complex pretreated DCs. The complete rejection of tumors occurred when immunization with CHP-HER2 complex pretreated DCs was started 10 days after tumor inoculation. Therefore, bone marrow-derived DCs pretreated with hydrophobized polysaccharide/oncoprotein complex are a powerful tool for enhancing the effectiveness of oncoprotein for anti-tumor vaccination, opening new options for immune cell therapy.

Animals↗

PubMed1998

Self-assembled hydrogel nanoparticle of cholesterol-bearing pullulan as a carrier of protein drugs: complexation and stabilization of insulin.

Insulin (Ins) spontaneously and easily complexed with the hydrogel nanoparticle of hydrophobized cholesterol-bearing pullulan (CHP) in water. The complexed nanoparticles (diameter 20-30 nm) thus obtained formed a very stable colloid. The thermal denaturation and subsequent aggregation of Ins were effectively suppressed upon complexation. The complexed Ins was significantly protected from enzymatic degradation. Spontaneous dissociation of Ins from the complex was barely observed, except in the presence of bovine serum albumin. The original physiological activity of complexed Ins was preserved in vivo after i.v. injection.

Animals↗

PubMed1998

A novel hydrophobized polysaccharide/oncoprotein complex vaccine induces in vitro and in vivo cellular and humoral immune responses against HER2-expressing murine sarcomas.

To elicit specific cellular immune responses against cancer, the development of efficient devices to deliver tumor antigen peptides to the MHC class I pathway constitutes a central issue. We report here a novel formula of hydrophobized polysaccharide nanoparticles, which can deliver a HER2 oncoprotein containing an epitope peptide to the MHC class I pathway. A protein consisting of the 147 amino-terminal amino acids of oncogene erbB-2/neu/HER2 (HER2) was complexed with two kinds of hydrophobized polysaccharides, cholesteryl group-bearing mannan (CHM) and cholesteryl group-bearing pullulan (CHP), to form nanoparticles (CHM-HER2 and CHP-HER2). CHM-HER2 and CHP-HER2 were able to induce CD3+/CD8+ CTLs against HER2-transfected syngeneic fibrosarcoma cell lines. In contrast, the oncoprotein alone failed to do so. These CTLs were Kd-restricted and specifically recognized a peptide (position 63-71) that was a part of a truncated HER2 protein used as an immunogen. In addition, vaccination by CHM-HER2 complexes led to a strongly enhanced production of IgG antibodies against HER2, whereas vaccination with HER2 proteins alone resulted in a production of antibodies at a marginal level. Mice immunized with CHM-HER2 or CHP-HER2 before tumor challenge successfully rejected HER2-transfected tumors. The complete rejection of tumors also occurred when CHM-HER2 was applied not later than 3 days after tumor implantation. In the effector phase of in vivo tumor rejection, CD8+ T cells played a major role. The results suggest that a sort of hydrophobized polysaccharide may help soluble proteins to induce cellular immunity as well enhance humoral immunity; hence, such a novel vaccine may be of potential benefit to cancer prevention and cancer therapy.

Animals↗

PubMed1998

Mechanism of beta-adrenergic receptor upregulation induced by ACE inhibition in cultured neonatal rat cardiac myocytes: roles of bradykinin and protein kinase C.

BACKGROUND: Although bradykinin is thought to contribute to the effects of ACE inhibitors on the cardiovascular system, its precise role remains to be elucidated. Evidence suggests that bradykinin might be important in the upregulation of beta-adrenergic receptors (beta-ARs) induced by ACE inhibitors, and the role of bradykinin in this effect has now been investigated with cultured neonatal rat cardiac myocytes. METHODS AND RESULTS: The density of beta-ARs on the myocyte surface was determined with a binding assay with [3H]CGP-12177. Incubation of cultured myocytes for 24 hours with the ACE inhibitor captopril (1 micromol/L) increased beta-AR density by 35% and enhanced the response of cells to isoproterenol but not to forskolin. Neither an angiotensin-II type 1 (AT1) receptor antagonist, CV-11974, nor angiotensin-I affected beta-AR density. However, the bradykinin B2 receptor antagonist Hoe 140 abolished the effect of captopril on beta-AR upregulation in a dose-dependent manner. The protein kinase C inhibitor staurosporine (20 nmol/L) but neither indomethacin nor L-NAME also inhibited captopril-induced upregulation of beta-ARs. Exogenous bradykinin increased the spontaneous beating frequency of cultured myocytes and Hoe 140 abolished this effect. Bradykinin level in the medium increased 1.4-fold by the treatment of cultured myocytes with captopril for 24 hours. CONCLUSIONS: The results suggest that captopril enhances beta-AR responsiveness by inducing beta-AR upregulation and that the latter effect is mediated by activation of bradykinin B2 receptors and protein kinase C. These observations also offer insight into the different roles of ACE inhibitors and AT1 receptor antagonists in the treatment of heart failure.

Adrenergic beta-Agonists↗