Two distinct alpha 1-adrenoceptor subtypes in rabbit liver: a binding study

1. The characteristics of alpha 1-adrenoceptor subtypes present on rabbit liver membranes were determined by radioligand binding and compared with the characteristics of binding in rat liver. 2. In saturation experiments using rabbit liver, [3H]-prazosin bound to two distinct affinity sites (pKD = 10.3 +/- 0.19 and 8.13 +/- 0.17, Bmax = 11.6 +/- 3.3 and 657.8 +/- 198.0 fmol mg-1 protein, respectively). In studies using rat liver, [3H]-prazosin bound to a single affinity site (pKD = 9.98 +/- 0.27, Bmax = 190.5 +/- 38.5 fmol mg-1 protein). 3. In competition experiments, unlabelled prazosin displaced biphasically the binding of 200 pM [3H]-prazosin to the rabbit liver; the resulting two pK1 values (9.85 +/- 0.08 and 8.01 +/- 0.09) were consistent with the affinity constants obtained in the saturation experiments. Two sites were also recognized by doxazosin (pKI 9.73 +/- 0.78 and 8.12 +/- 0.34), 2-(2,6-dimethoxy phenoxyethyl)-aminomethyl-1,4-benzo-dioxane (WB4101) pKI (9.74 +/- 0.32 and 7.57 +/- 0.34) and 5-methylurapidil (pKI 8.69 +/- 0.27 and 6.75 +/- 0.35), and the population of low affinity sites for the three antagonists was approximately 70%. Two distinct affinity constants (pKI 8.55 +/- 0.09 and 7.90 +/- 0.09) were also calculated for alpha-ethyl-3,4,5-trimethoxy-alpha-(3-((2-(2-methoxyphenoxy) ethyl)-amino)-propyl)-benzeneacetonitrile fumarate (HV723). 4. By contrast, [3H]-prazosin binding sites of rat liver membranes were detected as a single population with a high affinity for prazosin (pKI 10.01 +/- 0.08), and doxazosin (pKI 9.67 +/- 0.20) but with a low affinity for WB4101 (pKI 8.25 +/- 0.09), 5-methylurapidil (pKI 7.22 +/- 0.01) and HV723 (pKI 8.88 +/- 0.05). 5. These results indicate the presence of two distinct alpha 1-adrenoceptor subtypes in the rabbit liver, but only a single site in rat liver. The pharmacological characteristics of prazosin-high and -low sites in rabbit liver suggest identity with alpha 1A and putative alpha 1L subtypes, respectively. The site in rat liver is of the alpha 1B subtype.

Administration of rhG-CSF increases complete remission rates after CHOP and ProMACE/CytaBOM for non-Hodgkin's lymphoma: a pilot study. Hokkaido Study Group of Malignant Lymphoma and rhG-CSF

To evaluate the clinical effects of the administration of recombinant human granulocyte-stimulating factor (rhG-CSF) post chemotherapy for patients with advanced-staged intermediate-grade or high-grade non-Hodgkin's malignant lymphoma (NHL), we conducted this multicenter study and compared the responses between both the regimens, CHOP as a first-generation chemotherapy and ProMACE/CytaBOM as a third-generation chemotherapy, when combined with the rhG-CSF administration. In this multicenter study, where forty patients were registered, patients in both the CHOP and ProMACE/CytaBOM groups were treated with the original regimen designs without the necessity of reducing drug dosages when combined with the administration of rhG-CSF. The administration of rhG-CSF post both of the cytotoxic therapies brought about much higher rates of complete remission in both the groups (CHOP, 75 percent; ProMACE/CytaBOM, 75 percent), as compared with those of the previous study without the rhG-CSF administration. Regarding response rates according to the International prognostic factor index, the CHOP group showed a lower rate of complete remission in patients with risk factors, compared with ProMACE/CytaBOM group. This result suggested that the administration of rhG-CSF may offer one important approach for improving the first-line therapy for aggressive NHL with high risk factors.

Identification of alpha 1-adrenoceptor subtypes in the rabbit prostate

1. The alpha 1-adrenoceptor subtypes of rabbit prostate were characterized in binding and functional experiments. 2. In saturation experiments, [3H]-prazosin bound to two distinct affinity sites in the rabbit prostate (pKD = 11.20 +/- 0.22 and 8.39 +/- 0.11, Bmax = 15.3 and 736 fmol mg protein-1). 3. In the displacement experiments, the binding was inhibited with shallow displacement curves by unlabelled prazosin, WB4101, and 5-methylurapidil, suggesting the presence of two distinct affinity sites for prazosin, WB4101, or 5-methylurapidil. On the other hand, HV723 displaced the [3H]-prazosin binding monophasically with a low affinity. From the results, the presence of two distinct alpha 1-adrenoceptor subtypes was suggested; presumably one is the classical alpha 1A (cloned alpha 1C) subtype with high affinity for prazosin, WB4101 and 5-methylurapidil but not for HV723 and the other corresponds to the alpha 1L subtype, which shows low affinity for the four antagonists. 4. In the functional experiments, prazosin, WB4101, HV723 and 5-methylurapidil competitively antagonized the contractile response to noradrenaline with low affinities close to those for the alpha 1L subtype determined in binding experiments. These results suggest that contractile response to noradrenaline in the rabbit prostate is predominantly mediated through the alpha 1L subtype.

Incidence and risk factors of vascular dementia and Alzheimer's disease in a defined elderly Japanese population: the Hisayama Study

We followed 828 nondemented residents of Hisayama Town, Kyushu, Japan, aged 65 years or older (88.3% of the elderly population) for 7 years starting in 1985 in order to determine the type-specific incidence of dementia and its risk factors in the general Japanese population. Only two subjects were lost to the follow-up, during which period 103 subjects developed dementia. Morphologic examination of the brains of 89 subjects (86.4%) was made by autopsy or CT. We made the initial diagnosis of dementia based on the DSM-III-R criteria, with the diagnoses of vascular dementia (VD) being based on the NINDS-AIREN criteria and Alzheimer's disease (AD) on the NINCDS-ADRDA criteria. The incidence of VD and AD increased with age for both sexes. The age-adjusted total incidence (per 1,000 person-years) of dementia was 19.3 for men and 20.9 for women. The corresponding rates for VD were 12.2 for men and 9.0 for women, and for AD, 5.1 for men and 10.9 for women. Among the VD subjects whose brain morphology we examined, the most frequent type of stroke was multiple lacunar infarcts (42%), but half these subjects lacked a stroke episode in their histories. Multivariate analysis showed that age, prior stroke episodes, systolic blood pressure, and alcohol consumption were significant independent risk factors for the occurrence of VD. In contrast, age and a low score on Hasegawa's dementia scale were significant risk factors for AD, and physical activity was a significant preventive factor for AD.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergen-specific human T cell clones produce interleukin-5 upon stimulation with the Th1 cytokine interleukin-2

CD4+ T cell clones specific for Der fII (a major allergen of the house dust mite) were established from peripheral blood mononuclear cells of atopic patients. All of the T cell clones were classified as having the Th0 phenotype, since they produced both interleukin (IL)-2 and IL-4 upon stimulation. Some of the clones produced IL-5 upon antigenic stimulation. Human recombinant IL-2 induced these T cell clones to express IL-5 mRNA and produce IL-5 protein in a dose-dependent manner. IL-2 did not induce IL-4 production, indicating a discrete signal requirement for IL-4 versus IL-5 production by T cells. Moreover, IL-5 production induced by immobilized anti-CD3 monoclonal antibody was completely suppressed by the addition of anti-IL-2 monoclonal antibody, suggesting that IL-5 production, designated as a Th2-type immune response, is dependent on IL-2, a Thl cytokine. IL-2 produced at the site of allergic inflammation may contribute to IL-5 production by T cells in vivo.

Effects of rhG-CSF on infection complications and impaired function of neutrophils secondary to chemotherapy for non-Hodgkin's lymphoma. Hokkaido Study Group of Malignant Lymphoma, and rhG-CSF, Japan

It has been previously demonstrated that the administration of recombinant human granulocyte-colony stimulating factor (rhG-CSF) ameliorates the decrease of the polymorphonuclear neutrophils (PMNs) count after the cytotoxic chemotherapies, thereby reducing the infection complications associated with neutropenia. In this multi-center study, we studied the prophylaxtic effect of rhG-CSF administration on infection complications in patients with non-Hodgkin malignant lymphoma, who received cytotoxic chemotherapies (CHOP or ProMACE/CytaBOM). rhG-CSF administration reduced the frequency of infection complications, and there was no obvious difference in it's frequency between the CHOP-treated and the ProMACE/CytaBOM-treated groups when administered with rhG-CSF, thereby indicating that third generation therapy for NHL may be safely completed in Japanese in combination with rhG-CSF administration. Furthermore, we investigated both the in vitro and the in vivo effects of rhG-CSF on the function of PMNs in patients with NHL and healthy donors, and revealed that the administration of rhG-CSF for NHL patients receiving cytotoxic chemotherapy brought on an improvement of the production of active oxygen but did not affect serum levels of IFNs, IL-1-beta, and IL-6, inspite of a slight elevation of TNF-alpha. Consistent with these results, in vitro treatment of PMNs with rhG-CSF induced no significant production of these inflammatory cytokines and their mRNA expressions. Furthermore, rhG-CSF administration showed no significant effects in vivo on the expression of CD11a, CD11b and LECAM-1 on PMNs and integrins on platelets.

Relationship between insufficient redistribution in exercise thallium-201 myocardial single-photon emission computed tomography and reverse redistribution at rest

It is widely accepted that perfusion defects in 3 to 4-h delayed images in exercise thallium-201 (201Tl) myocardial scintigraphy underestimate the viability of myocardium in the infarct region. In the present study, to examine the contribution of the condition of myocardium which demonstrates reverse redistribution in resting scintigraphy to the insufficiency of redistribution in the 4-h delayed image in exercise scintigraphy, we performed exercise and resting 201Tl myocardial single-photon emission computed tomography in 58 patients with acute myocardial infarction and a single diseased coronary artery. Twenty eight patients demonstrated reverse redistribution (group RR) and 28 showed a fixed defect (group FD) in resting scintigraphy. Redistribution in the 4-h delayed image in exercise scintigraphy was significantly more insufficient in group RR than in group FD (p < 0.01), and the degree of the insufficiency of redistribution in exercise scintigraphy closely correlated with the degree of reverse redistribution in resting scintigraphy (r = 0.79, p < 0.001). We conclude that in patients with acute myocardial infarction, the condition of myocardium which demonstrates reverse redistribution in resting myocardial scintigraphy is related to the insufficiency of redistribution in the delayed image in exercise scintigraphy.

Pharmacological profiles of a novel alpha 1-adrenoceptor agonist, PNO-49B, at alpha 1-adrenoceptor subtypes

The effects of a newly synthesized compound, PNO-49B, (R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethanesulfonanilide hydrochloride, on alpha 1-adrenoceptor subtypes were examined in various tissues in which the following distribution of alpha 1-adrenoceptor subtypes has been suggested: dog carotid artery (alpha 1B), dog mesenteric artery (alpha 1N), rabbit thoracic aorta (alpha 1B + alpha 1L), rat liver (alpha 1B), rat vas deferens (alpha 1A + alpha 1L), rat cerebral cortex (alpha 1A + alpha 1B) and rat thoracic aorta (controversial subtype). PNO-49B (0.1-100 microM) produced concentration-dependent contractions in dog mesenteric artery, rabbit thoracic aorta, rat thoracic aorta and rat vas deferens; and the maximal amplitudes of contraction were almost the same as or slightly less than those of noradrenaline. By contrast, the maximal response to PNO-49B in dog carotid artery was markedly smaller than the response to noradrenaline. In rabbit thoracic aorta, the contractile response to PNO-49B was not affected by inactivation of the alpha 1B subtype with chloroethylclonidine (CEC), although the response to noradrenaline was attenuated by that treatment. The dissociation constants (KA) of PNO-49B were not different among the rat thoracic aorta, dog carotid and mesenteric arteries and rabbit thoracic aorta (CEC-pretreated). The contractile responses to PNO-49B were inhibited competitively by prazosin, HV723 (alpha-ethyl-3,4,5-trimethoxy-alpha-(3-((2-(2-methoxyphenoxy)-ethyl)- amino(propyl)benzeneacetonitrile fumarate) and by WB4101 (2-(2,6-dimethoxyphenoxyethyl)-aminomethyl-1,4- benzodioxane).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological characterization of alpha 1-adrenoceptor subtypes in the human prostate: functional and binding studies

OBJECTIVE

To characterize the alpha 1-adrenoceptor subtypes of the human benignly enlarged prostate using functional and binding studies.

MATERIALS AND METHODS

Strips of prostatic tissue taken from nine patients with benign prostatic hypertrophy who were undergoing open prostatectomy were used in the study.

RESULTS

The strips isolated from five prostates produced a large contraction in response to noradrenaline and phenylephrine but not to clonidine. The contractile response induced by noradrenaline was competitively antagonized by representative alpha 1-adrenoceptor antagonists (prazosin, WB4101, 5-methylurapidil and HV723), the dissociation constants (pKB) being < 8.5. Pre-treatment with chloroethylclonidine was without effect on the contractile response to noradrenaline. In saturation experiments with five prostates, [3H]-prazosin bound to the prostate membranes with two distinct affinities (pKD = 9.95 +/- 0.07 and 8.71 +/- 0.04, Bmax = 151 +/- 8 and 138 +/- 3 fmol/mg protein, respectively). Unlabelled prazosin and WB4101 biphasically displaced the binding of 200 pM [3H]-prazosin; the resulting high and low pKI values for each of the antagonists were consistent with the two pKD values obtained for [3H]-prazosin in the saturation experiments. 5-Methylurapidil and HV723 displaced the [3H]-prazosin binding monophasically with an affinity (pKI) close to 8.5.

CONCLUSIONS

These results suggest the presence of at least two distinct alpha 1-adrenoceptor subtypes (presumably an alpha 1C subtype with a high affinity for prazosin and WB4101, and a putative alpha 1L subtype with a low affinity for the antagonists) in the human prostate, in which the latter subtype may be predominantly involved in the contractile response to noradrenaline.

Hyperinsulinaemia and blood pressure in a general Japanese population: the Hisayama Study

OBJECTIVES

To study the relationship between serum insulin and blood pressure, as well as the prevalence of hypertension according to the insulin level in a general Japanese population.

DESIGN

In 1988 a cross-sectional community survey was conducted among Hisayama residents aged 40-79 years.

METHODS

A total of 1073 males and 1407 females (72.5 and 80.5% of the total population, respectively) underwent comprehensive investigation, including a 75-g oral glucose-tolerance test. Fasting and 2-h serum insulin levels were measured by radioimmunoassay.

RESULTS

The sum of the fasting and 2-h postloading insulin levels was significantly correlated with the systolic blood pressure (SBP; r = 0.18 and 0.26 for males and females, respectively) and the diastolic blood pressure (DBP; r = 0.24 and 0.19, respectively) in the subjects not receiving antihypertensive drugs. In multiple regression analysis the correlation with blood pressure remained significant in both sexes even after controlling for age, body mass index, alcohol intake, smoking, a family history of hypertension, serum total cholesterol and fasting plasma glucose. The age- and sex-adjusted prevalence of hypertension (SBP > or = 160 mmHg or DBP > or = 95 mmHg, or both, or receiving drug treatment) increased significantly with an increase in the sum of fasting and 2-h postload insulin levels in both the non-obese subjects (body mass index < 25 kg/m2) and the obese subjects (body mass index > or = 25 kg/m2). Multiple logistic regression showed that the sum of fasting and 2-h postload insulin levels was a significant factor with an independent relationship to hypertension, even after taking the other risk factors into account.

CONCLUSION

The present study suggests that hyperinsulinaemia is related to hypertension in a general Japanese population.

[Mortality from major causes of death and its risk factors in the elderly--26-year follow-up study in Hisayama]

The authors studied mortality from major causes of death and risk factors in the elderly in a long-term prospective survey conducted in a Japanese suburban community, Hisayama. In the baseline survey in 1961, we scrutinized 1658 residents of the town aged 40 years or older accounting for 92% of the total population in this age range. Of those, 591 residents (245 men and 346 women) aged 60 years or older, who were free from major cardiovascular disease, were selected for the present study. They were followed-up for 26 years from 1961 to 1987. The average age was 67 years for men and 70 years for women, being significantly higher for women than for men. During the follow-up period, 529 subjects (89.5%) died, and 448 were autopsied (autopsy rate 84.7%). The all-cause mortality (per 1,000 person-years) after adjustment for age was 89.9 for men and 56.7 for women, the former being significantly higher than the latter (p < 0.01). The age-adjusted mortality from cerebrovascular disease was estimated to be 21.4 for men and 9.9 for women, i.e. 8.9 and 8.8 from heart disease, and 19.9 and 10.6 from neoplasm, and 18.1 and 12.2 from-pneumonia, respectively. There was significant sex difference in mortality from cerebrovascular disease, neoplasm and pneumonia (p < 0.01) but not from heart disease (p > 0.1). Multiple Cox's proportional hazards regression analysis showed systolic blood pressure and male sex to be significant risk factors for death by cerebrovascular disease. Systolic blood pressure was also a predictor for death by heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

The association of the insulin resistance syndrome with impaired glucose tolerance and NIDDM in the Japanese general population: the Hisayama study

To elucidate the risk factors for initiating glucose intolerance, the relevant factors were explored in a cross-sectional survey conducted in a sample population aged 40-79 years old selected from a Japanese community, Hisayama, Japan in 1988. A 75-g oral glucose tolerance test was used to classify 1,073 men (72.5% of the entire population in the same age range) and 1,407 women (80.5%) into normal, impaired glucose tolerance and diabetes mellitus groups. In all age and sex groups with normal glucose tolerance, the sum of fasting and 2-h post-load insulin values varied widely and demonstrated significant positive correlations with triglycerides, body mass index, waist-hip ratio, systolic and diastolic blood pressure, while it negatively correlated to HDL cholesterol (p < 0.05). Insulin resistance was presumed to develop in normal glucose tolerance subjects with hyperinsulinaemia. The sum of the insulin concentrations, triglycerides, body mass index, waist-hip ratio and blood pressure levels was significantly associated with impaired glucose tolerance in all age and sex groups after adjustment for age (p < 0.05) and was also related to diabetes in either all or some age and sex groups, respectively (p < 0.05). It was shown that glucose intolerance in the general population was associated with the factors related to insulin resistance. These cross-sectional data, therefore, support the hypothesis that insulin resistance is the primary defect in the development of glucose intolerance in the Japanese general population. However, a further prospective study is still needed in order to confirm this hypothesis.

The positive and negative cis-acting elements for methanol regulation in the Pichia pastoris AOX2 gene

The methylotrophic yeast Pichia pastoris has two alcohol oxidase genes, AOX1 and AOX2. The AOX2 gene is transcribed at a much lower level than the AOX1 gene. Apart from this difference in expression levels, the two genes are regulated similarly. To study the role of cis-acting elements in the promoter region of the AOX2 gene, we constructed expression plasmids in which the human serum albumin (HSA) gene was placed under the control of various deleted or mutated AOX2 promoter derivatives. By analyzing the expression of HSA in P. pastoris transformants, we have identified three cis-acting regulatory elements in the AOX2 promoter. The positive cis-acting element AOX2-UAS, located between positions -337 and -313 (relative to the transcription initiation codon), is required for response to transcriptional induction by methanol in an orientation-independent manner, and artificial amplification of the AOX2-UAS resulted in an increase in the transcriptional activity of the promoter. A sequence homologous to AOX2-UAS was also found in the AOX1 promoter, and in methanol-regulated promoters in other methylotrophic yeast. Two negative cis-acting elements, AOX2-URS1 and AOX2-URS2 play a role in repressing transcription from the AOX2 promoter. The function of AOX2-UAS is completely repressed by this unique repression system when both the AOX2-URS1 and AOX2-URS2 are functional.

Development and characterization of chimeric anti-carcinoembryonic antigen monoclonal antibodies and their Fab fragments

In an attempt to reduce the immunogenicity of two different murine anti-carcinoembryonic antigen (CEA) monoclonal antibodies (MAbs), KM10 and A10, we produced recombinant mouse/human chimeric MAbs and the respective Fab fragments carrying the variable regions of the murine MAbs. Chimeric A10 Fab fragment was expressed in Escherichia coli, and produced in large quantities in a mini-jar fermentation system. In competitive binding assays, chimeric MAbs and their Fab fragments showed identical specificity to human CEA epitopes, as compared to the parental MAbs or Fab fragments. Both chimeric Fab fragments exhibited strong immunohistochemical reactivity with various gastrointestinal carcinomas and no reactivity with CEA-related antigens, such as NCA (nonspecific cross-reacting antigen) or BGPI (biliary glycoprotein I). Furthermore, chimeric KM10 MAb elicited substantially higher antibody-dependent cellular cytotoxicity than the murine MAb. Complement-dependent cytotoxicity in vitro was much weaker with chimeric KM10 MAb. These results indicate that chimeric MAbs or Fab fragments could potentially replace the parental murine antibodies or their Fab fragments in therapy or diagnosis of human gastrointestinal carcinomas.

Changing patterns in the prevalence of dementia in a Japanese community: the Hisayama study

We compared type-specific prevalences of dementia between two surveys of Hisayama residents > or = 65 years old conducted in 1985 and 1992. The overall age-adjusted prevalence was greatly decreased from 5.4% in 1985 to 3.3% in 1992 for men, while it was changed little from 7.5 to 6.3% for women. The prevalence of vascular dementia (VD) decreased during the intervening 7 years in men but not in women. The prevalence of Alzheimer's type (SDAT) was the same in either sex. The ratio of VD to SDAT prevalence was 1.8 in 1985 but fell to 1.1 in 1992. The background factors responsible for this change are discussed.

Prevalence of type 2 (non-insulin-dependent) diabetes mellitus and impaired glucose tolerance in the Japanese general population: the Hisayama Study

We determined the population-based prevalence of diabetes mellitus in members of the Japanese community, Hisayama aged 40-79 years old by a 75-g oral glucose tolerance test. The basic population used to calculate diabetic prevalence was 1,077 men (72.8% of the whole population in the same age range) and 1,413 women (80.8%) including ten diabetic patients on insulin therapy. In addition, we compared the prevalence of history of diabetes which was acquired by interview or questionnaire, between participants and non-participants in the 75-g oral glucose tolerance test, but they were not statistically different. The age-adjusted prevalence of diabetes to world population was 12.7% for men and 8.4% for women, and that of impaired glucose tolerance was 19.6% for men and 18.4% for women. These figures were much higher than those previously reported from several Japanese communities. The results obtained from the present study could reveal true prevalence of diabetes among the Japanese population. In addition, the reasons for the increasing prevalence of diabetes among the recent Japanese population are also discussed.

Role of surgical treatment for recurrent hepatocellular carcinoma after hepatic resection

From 1978 to 1989, 164 patients underwent hepatic resection for hepatocellular carcinoma at our institution. The carcinoma was resected completely in 149 patients. Sixteen patients were excluded from this study because it was not known whether they were recurrent or disease free, or because death occurred as a result of surgical complications. Recurrent disease occurred in 48.1% of the remaining 133 patients. Fifty-seven patients had recurrent tumor only in the residual liver. A second hepatic resection was performed in 14 cases, 22 received intraarterial chemotherapy and/or arterial embolization without resection,a nd the remaining 21 received no anticancer therapy. The 5-year survival rate of patients who had a second resection was 92.0%. Recurrences in distant organs occurred in 14 patients, and the recurrent carcinoma was resected in five cases. Four of these 5 patients survived more than 3 years after the second surgery. Aggressive surgical resection of recurrent HCC, even for distant metastasis, is a viable approach, and may produce long-term survivors.

Phylogenetic relationships of turfgrasses as revealed by restriction fragment analysis of chloroplast DNA

Chloroplast DNAs (cpDNAs) were analyzed in order to clarify the phylogenetic relationships among turfgrasses. Physical maps of cpDNAs from Agrostis stolonifera and Zoysia japonica, which are representative species of cool (C3 type) and warm (C4 type) season turfgrasses, respectively, were constructed with four restriction enzymes, i.e., PstI, SalI, SacI, and XhoI. The genome structures of these cpDNAs were found to be similar to each other in terms of genome size and gene orders, showing thereby a similarity to other grass cpDNAs. CpDNAs of 5 species of cool season turfgrasses and 6 species of warm season turfgrasses as well as four species of cereals, distributed among 14 genera of Gramineae, were digested with PstI, XhoI, and BamHI, and their restriction fragment patterns were compared. Their genome sizes were estimated to be 135-140 kbp. Each species showed characteristic RFLP patterns. On the basis of the frequency of commonly shared fragments, a dendrogram showing the phylogenetic relationships among their cpDNAs was constructed. This dendrogram shows that turfgrasses can be divided into three major groups; these correspond to the subfamilies. Cool and warm season turfgrasses are clearly distinguishable from each other, and the latter can be further classified into two subgroups that correspond to Eragrostoideae and Panicoideae. Our classification of turfgrasses and cereals by RFLP analysis of cpDNA agreed in principal with their conventional taxonomy, except for the location of Festuca and Lolium.

[The expression of osteoblastic features in a SV40 large T antigen immortalized mouse calvarial cell line]

A new cell line (VMCs) was established from the mouse calvarial cells transfected with the plasmid (pMT1-neo) containing a SV40 large T antigen gene and neomycin-resistance gene. The VMCs cell has been subcultured weekly for over 100 passages at the ratio of 1:20-1:60. Their population doubling time was about 15 hours. The VMCs cell seemed to be fibroblast-like monomorphic cells by a phase-contrast microscope. The cells were examined and characterized as osteoblastic features by alkaline phosphatase activity, bone formation in diffusion chamber and the expression of mRNAs of type I collagen and osteopontin. The features were as follows: 1. Alkaline phosphatase activity of the VMCs cell was low in growth phase but was increased by the treatment with retinoic acid. 2. Differentiation of the VMCs cell was examined by diffusion chamber implanted intraperitoneally into Balb/c mouse. Implants were sectioned and stained with hematoxylin-eosin, alizarin red S, von Kóssa, alcian blue or Azan. In the chambers formation of mineralized matrices and collagenous fibrils were observed. 3. Northern analysis demonstrated the expression of type I collagen and osteopontin mRNAs. Osteopontin mRNA was increased by the treatment with 1 alpha,25(OH)2D3 or retinoic acid. These results suggest that the VMCs cell have some properties of the osteoblast and consider to be useful for the study of bone formation and the biocompatibility test for the dental or medical materials.

Establishment of a novel monoclonal antibody, SE-1, which specifically reacts with rat hepatic sinusoidal endothelial cells

A monoclonal antibody, SE-1, which specifically reacted with rat hepatic sinusoidal endothelial cells (HSE), was established with elutriator-separated HSE as immunogen. No crossreactivity was observed with other types of endothelial cells or non-endothelial cells. By immunoelectron microscopy, the antigen recognized by MAb SE-1 was localized to the membrane surface of HSE. Immunoblot analysis revealed that SE-1 recognized a single 45 KD band. Although the SE-1 antigen is not yet characterized, the above evidence strongly suggests that it is related to the specific function of HSE. Therefore, SE-1 may be a useful marker to study the role of HSE in various pathophysiological conditions of the liver.

[Hyperinsulinemia and hypertension in an elderly Japanese population--the Hisayama Study]

Hyperinsulinemia has been closely associated with hypertension in several epidemiological studies, but little is known about this condition in the elderly. The authors studied the relationship between serum insulin and blood pressure levels, and the prevalence of hypertension according to insulin levels in the elderly in a Japanese rural community, Hisayama. In 1988, 75 g oral glucose tolerance test was performed on 426 male and 567 female Hisayama residents aged 60 to 79 years. Fasting and 2 hr serum insulin values were measured by radioimmunoassay. In the subjects, excluding those receiving antihypertensive drugs, the sum of fasting and 2 hr postload insulin (sigma IRI) significantly correlated with systolic (r = 0.15 and 0.25 for males and females, respectively) and diastolic blood pressure (r = 0.20, 0.16). In multiple regression analyses, the correlation with systolic blood pressure remained significant in females after controlling for age, body mass index, alcohol intake, smoking habits, serum total cholesterol, HDL-cholesterol, triglycerides, and fasting plasma glucose. In contrast, sigma IRI did not remain as an independent variable relevant to blood pressure among males. The age-adjusted prevalence rates of hypertension (> or = 160/95 mmHg or receiving drug treatment) significantly increased with increasing quartiles of sigma IRI in females. The prevalence of hypertension which was not treated with drugs also increased significantly with increasing sigma IRI in females. However, no significant association was observed in males. In conclusion, the present study suggests that hyperinsulinemia can be related to hypertension in the female elderly in the general population of Japan.

Identification of alpha 1-adrenoceptor subtypes in the dog prostate

The alpha 1-adrenoceptor subtypes of dog prostate were characterized in binding and functional experiments. In saturation experiments, [3H]prazosin bound to alpha 1-adrenoceptors with high affinity. In the displacement experiments, unlabelled prazosin and WB4101 biphasically inhibited the binding of 400 pM [3H]prazosin, suggesting the presence of at least two distinct affinity sites for prazosin or WB4101. The proportion of high-affinity sites was approximately 10%. HV723 also recognized two distinct affinity sites but the proportion of high-affinity sites was approximately 20%. From these results the presence of three distinct alpha 1-adrenoceptor subtypes was suggested: presumably subtypes alpha 1A (high affinity for prazosin and WB4101), alpha 1N (high affinity for only HV723) and alpha 1L (low affinity for the three antagonists) according to the recently proposed alpha 1-adrenoceptor subclassification. The density of subtype alpha 1L was much higher than that of subtypes alpha 1A and alpha 1N subtypes. In the functional experiments, prazosin, WB4101 and HV723 competitively antagonized the contractile response to noradrenaline with low affinities close to those estimated for the alpha 1L subtypes. These results suggest that the contractile response to noradrenaline in the dog prostate is mediated predominantly through alpha 1L subtype alpha-adrenoceptors.

Synthesis of galactose derivatives that render lectin-induced agglutinating ability to liposomes

Three galactose (Gal) derivatives, Gal beta 1-n-C16H33 (1), Gal beta (1-4)-Glc beta 1-n-C16H33 (2), and Gal beta 1-(CH2CH2O)3-n-C16H33 (3), were synthesized and incorporated into liposomes prepared from egg yolk lecithin. Agglutination of these liposomes with Ricinus communis agglutinin was examined by following the change of turbidity. Liposomes containing 3 were effectively agglutinated in contrast to the cases of 1 and 2, suggesting that the oxyethylene groups act as a favorable spacer to extrude Gal groups into the water. Differential scanning calorimetry showed that 3 was mixed with egg yolk lecithin at room temperature, but 1 and 2 were in the gel state, resulting in the phase separation that makes the recognition of Gal residue with Ricinus communis agglutinin difficult.

Identification of alpha 1-adrenoceptor subtypes in the rat vas deferens: binding and functional studies

1. The alpha 1-adrenoceptor subtypes of the prostatic and epididymal portion of rat vas deferens were characterized in binding and functional experiments. 2. In saturation experiments, [3H]-prazosin bound to two distinct affinity sites in the epididymal portion of rat vas deferens (pKD = 10.1 +/- 0.13 and 9.01 +/- 0.15, Bmax = 507 and 1231 fmol mg-1 protein, respectively). In the prostatic portion [3H]-prazosin bound to a single affinity site (pKD = 9.82 +/- 0.04, Bmax = 924 fmol mg-1 protein). 3. In the displacement experiments, unlabelled prazosin displaced biphasically the binding of 200 pM [3H]-prazosin to the epididymal portion; the resulting two pKI values were consistent with the affinity constants obtained in the saturation experiments. WB4101 (2-(2,6-dimethoxy-phenoxyethyl)-amino-methyl-1,4-benzodioxane) and benoxathian also discriminated the two affinity sites in the epididymal portion and the population of low affinity sites for the three antagonists was approximately 40%. On the other hand, the prostatic portion predominantly showed a single affinity site for prazosin, WB4101 and benoxathian, although the presence of a small proportion (less than 10%) of the low affinity site could be detected. HV723 (alpha-ethyl-3,4,5-trimethoxy-alpha-(3-((2-(2-methoxyphenoxy)ethyl)-a min o)- propyl) benzeneacetonitrile fumarate) displaced the [3H]-prazosin binding monophasically with a low affinity in both halves. 4. Pretreatment with chlorethylclonidine (CEC) at concentrations higher than 1 microM inhibited 700 pM [3H]-prazosin binding to the prostatic portion by approximately 50%. However, the inhibition in the epididymal portion was much less (approximately 21% at 50 microM CEC).5. In the functional study, the contractile response to noradrenaline was competitively inhibited by prazosin, WB4101, benoxathian and HV723 with similar and low affinities (pKB value ranging from 8.0to 9.0) in the epididymal portion of rat vas deferens. In the prostatic portion of rat vas deferens,noradrenaline also produced a contraction, but the maximal amplitude of contraction developed was approximately one-fourth of that in the epididymal portion. Prazosin and WB4101 also inhibited the contractile response of the prostatic portion with the pKB values similar to those obtained in the epididymal portion. The contractions to noradrenaline in both portions were potently attenuated by 1 LM nifedipine but were not affected by pretreatment with 1O LM CEC.6. Under conditions where P2x-purinoceptors and prejunctional M2-adrenoceptors were blocked, electrical transmural stimulation produced a rapidly developing phasic contraction and a subsequent tonic contraction in the epididymal portion of rat vas deferens. The phasic and tonic contractions were inhibited in a concentration-dependent manner by prazosin (ICs = 25.7 and 25.9 nm, respectively),WB4101 (ICo= 7.27 and 7.58 nM), benoxathian (ICs = 10.9 and 8.66 nM) and HV723 (ICs = 15.9 and 14.9 nM). Nifedipine selectively attenuated the tonic contraction induced by electrical stimulation, and the residual phasic response was inhibited by the antagonists mentioned above with similar affinities to those in the absence of nifedipine. CEC (10 gM) had little effect on the adrenergic neurogenic contractions.7. The present results indicate the presence of two distinct alpha&-adrenoceptor subtypes in the rat vas deferens, which show respectively high and low affinities for each of prazosin, WB4101 and benoxathian,and presumably correspond to putative MIA and alL subtypes according to the recent am-adrenoceptorsubclassifications. The contractions induced by exogenous and endogenous noradrenaline seem to be predominantly mediated through the alL subtype. The heterogeneous distribution of the low affinity sites(alL subtype) may well explain differences in functional responsiveness between the two portions of rat vas deferens.

Clinical significance of reverse redistribution on thallium-201 single-photon emission computed tomography in patients with acute myocardial infarction

To determine the clinical significance of reverse redistribution (RR), resting thallium-201 myocardial single-photon emission computed tomography was performed once or twice in 80 patients in subacute phase (1 week to 2 months) of myocardial infarction. Thirty eight patients demonstrated RR on at least one study (group RR) and 32 a fixed defect only (group FD). Group RR had significantly smaller defects than group FD. Standardizing the relation of the severity of wall motion abnormality of left ventricle on echocardiogram with that of perfusion defect, in group RR wall motion abnormality in the acute and subacute phase reflected the defect of delayed image, while that in chronic phase, which was thought to reflect the viability of myocardium in the infarct region, reflected the defect of initial image. In serial thallium-201 studies, only the defect of delayed image of group RR improved on the second study, while the defect of initial image of group RR and defect of group FD did not improve. Wall motion of group RR improved with the disappearance of RR, and when RR remained, wall motion did not improve so much. We concluded that RR was thought to be demonstrated in viable myocardium with severe wall motion abnormality.

Analysis of length and surface area of each segment of the large intestine according to age, sex and physique

Length, diameter and surface area of each of 6 segments of the large intestine were determined and calculated in 920 Japanese patients who underwent barium enema. Of the length and surface area measurements obtained, those of the transverse colon were the largest, followed by those of the sigmoid colon. The diameter of the ascending colon was the largest, while those of the descending colon and sigmoid colon were the smallest. There were various sex differences in size of the large intestine. Length and surface area of the entire large intestine in males were shorter and smaller respectively than those in females. Lengths of the cecum, ascending colon, transverse colon and rectum in males were shorter than those in females. Diameters of the descending colon, sigmoid colon and rectum in males were larger than those in females. Total surface areas of the ascending colon and transverse colon in males were smaller than those in females, while total surface areas of the descending colon, sigmoid colon and rectum in males were larger than those in females. Length of the entire large intestine tended to be increased with age. Length and surface area of the entire large intestine tended to be increased with an increase in physical dimensions in females.

A 68-kD GTP-binding protein associated with the T cell receptor complex

The identity of the guanine nucleotide-binding protein (G protein) involved in T cell activation pathways remains unclear. We identified a 68-kD GTP-binding protein associated with the T cell receptor (TCR)/CD3 complex using immunoprecipitation and GTP-affinity labeling techniques. Proteins coimmunoprecipitated with the TCR/CD3 complex in digitonin lysate of a human leukemic T cell line, MOLT 16, were incubated with alpha-[32P]GTP and irradiated with ultraviolet rays to covalently link the labeled GTP to GTP-binding proteins. They were then analyzed by electrophoresis. The 68-kD protein exhibited nucleotide specificity for GTP-binding and was insensitive to cholera and pertussis toxins. The 68-kD GTP-binding protein could be coimmunoprecipitated with the TCR/CD3 complex but not with other surface molecules such as major histocompatibility complex class I and lymphocyte function associated-1, which do not cause rapid Ca2+ mobilization. These suggest that the 68-kD GTP-binding protein is specifically associated with the TCR/CD3 complex.

A high resolution PET for animal studies

In the PET system a block detector, which is a position-sensitive photomultiplier (PMT) tube coupled to four arrays of 1.7-mm-wide BGO crystals, is utilized. Fifteen block detectors are positioned to form a 35-cm-diameter ring, with four BGO arrays coupled to each PMT. This provides four detector rings, giving the system a 7-slice imaging capability. The gantry head tilts up to +/-90 degrees , and is capable of moving up and down by 30 cm. These positioning capabilities allow flexibility and great ease of use in subject positioning. A gantry entrance size of 22 cm in diameter allows studies ranging from rats and mice to primates such as Rhesus and squirrel monkeys. The physical performance of the system has been evaluated.

Subtypes of alpha 1-adrenoceptors involved in noradrenaline-induced contractions of rat thoracic aorta and dog carotid artery

We tried to determine alpha 1-adrenoceptor subtypes involved in noradrenaline-induced contractions of rat thoracic aorta and dog carotid artery. Prazosin competitively antagonized the contractions induced by noradrenaline in both the arteries with a high pKB value (approximately 9.7). WB4101, benoxathian, phentolamine, HV723 and 5-methylurapidil also competitively antagonized the responses to noradrenaline in both the arteries: however, the affinities for the antagonists were significantly higher in the rat thoracic aorta than in the dog carotid artery. The affinities for the competitive antagonists were not changed by treatment with nifedipine. In the rat thoracic aorta, chlorethylclonidine (CEC) elicited either a persistent contraction with rhythmic activities before treatment with nifedipine or partial inactivation of alpha 1-adrenoceptors in the presence of nifedipine. On the other hand, CEC produced only inactivation of alpha 1-adrenoceptors in the dog carotid artery. These results suggest that noradrenaline-induced contractions of the rat thoracic aorta and dog carotid artery are respectively mediated through distinct alpha 1-adrenoceptor subtypes. According to the alpha 1A, alpha 1B subclassification, the alpha 1-adrenoceptor of dog carotid artery is like the alpha 1B subtype, while that of rat thoracic aorta is atypical. Both subtypes are also identified as a high affinity site for prazosin (alpha 1H subtype) in the alpha 1H, alpha 1L and alpha 1N subclassification.

Supersensitivity to tetrodotoxin and lignocaine of sea anemone toxin II-treated sodium channel in guinea-pig ventricular muscle

1. Sea anemone toxin II (ATX II, 20-30 nM) doubled the action potential duration in guinea-pig papillary muscles without affecting the maximum rate of rise of the action potential (Vmax) and the resting potential. 2. Tetrodotoxin and lignocaine shortened the prolonged action potential in the ATX II-treated papillary muscles in concentrations (30 nM - 3 microM) at which these drugs did not suppress the Vmax. 3. Whole-cell voltage-clamp experiments with single ventricular cells showed that ATX II produced a slowly decaying inward sodium current following a transient sodium current upon depolarization. 4. The ATX II-induced slowly decaying current was reduced by tetrodotoxin or lignocaine in concentrations (300 nM-1 microM for tetrodotoxin, 3-10 microM for lignocaine) at which these drugs failed to affect the Vmax in cells not treated with ATX II. 5. These results suggest that sodium channel modification by ATX II not only changes its kinetics but also increases the susceptibility of the channel to block by tetrodotoxin and lignocaine.

Relationship between length and surface area of each segment of the large intestine and the incidence of colorectal cancer

In investigating the occurrence and clinical characteristics of diseases of the large intestine, particularly tumors, the number, distribution, and incidence of the lesions were compared between segments of the large intestine. If the distribution and incidence of lesions are correlated with the length or surface area of each segment, the incidence of lesions will be the same throughout the large intestine. If the lesions are unrelated to length or surface area, the factors that affect the occurrence of lesions must be determined and will be characteristic for each segment. However, the length and surface area of each segment of the large intestine and the ratios of each to both the total length and surface area of the large intestine are not clear. In this study the length and surface area of each segment of the large intestine were measured and calculated using the barium enema technique, and the incidence rates of cancer per unit length and surface area of each segment were determined and compared.

Lowered responsiveness of bronchoalveolar lavage T lymphocytes in hypersensitivity pneumonitis

We previously reported that Trichosporon cutaneum was the major causative antigen of summer-type hypersensitivity pneumonitis (HP) in Japan. In summer-type HP patients, we noticed that the proliferative responses of bronchoalveolar lavage (BAL) lymphocytes to phytohemagglutinin (PHA) and concanavalin A were significantly lower than those of the peripheral blood lymphocytes of the same patients. It was shown in this study that the low response of BAL lymphocytes was due to an intrinsic lowering of the responsiveness of the T cells. Results of the mixed culture experiments, in which the responses to mitogens of BAL and peripheral blood T cells mixed with either alveolar macrophages or blood monocytes were compared, indicated that the decreased proliferative response was due neither to the suppressive effect nor to defects in accessory function of the alveolar macrophages. BAL T cells did not act as suppressor cells when they were added to the culture of peripheral T cells. The decreased proliferative response was not due to the dominance of CD8+ T cells frequently seen in BAL cells of HP patients, because both CD4+ and CD8+ T cells separated from BAL cells of HP patients showed lower responsiveness than those of peripheral blood T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

A case of cecocolic intussusception with complete invagination and intussusception of the appendix with villous adenoma

Villous adenoma of the appendix is a rare neoplasm and intussusception of the appendix is a rare pathologic condition. A very rare case seen in a 35-year-old male with pain in the right lateral abdomen is reported. In this patient, the appendix along with the villous adenoma intussuscepted and invaginated into the cecal lumen, and presented as cecocolic intussusception. A polypoid lesion was diagnosed in the cecum by fiberoptic colonoscopy. Unlike polypoid lesions at other sites in the large intestine, polypoid lesions of the cecum may accompany intussusception and invagination of the appendix. Consequently, caution is required in performing endoscopic polypectomy in cases of polypoid lesions of the cecum.

Causes of death in the elderly and their changing pattern in Hisayama, a Japanese community. Results from a long-term and autopsy-based study

The causes of death for the elderly were prospectively studied in Hisayama, Japan, a rural community. We compared 1,621 subjects, aged 40 years or over, recruited in 1961, and 2,053 subjects recruited in 1974. Each cohort was studied in a follow-up that lasted 10 years; they had autopsy rates of 82.1% and 86.1% during each 10-year period, respectively. The most common causes of death for those aged 70 years or over were cerebrovascular disease, malignant neoplasms, and pneumonia. Deaths due to cerebrovascular disease tended to decrease in the recent cohort, but the proportion of decline was more prominent in cases aged 40 to 69 years. There was a sex difference in the changing pattern of mortality from heart diseases including ischemic heart disease. Deaths by both heart diseases and ischemic heart disease increased in the more recent cohort of aged women, whereas they decreased in the aged men. Pneumonia was an important cause of death for the elderly in both cohorts. Deaths due to "senility" were rare, being only 1% of the deceased aged 70 or over. With prolonged lifespan, especially for women, the impact of atherosclerosis and its related disorders on the recent Japanese aged population appears to have increased.

New plastic-coated coaxial catheter system for superselective hepatic catheterization: technical note

With the use of a new improved coaxial catheter system, superselective hepatic catheterization has become easier. The improvements consist of a decrease in the outer and an increase in the inner diameters of the coaxial catheters from 0.98 to 0.96 mm and from 0.55 to 0.65 mm, respectively, and thickening of core guidewire material from 0.014 inch (0.35 mm) to 0.018 inch (0.40 mm). With this new catheter system, it is possible to inject contrast medium (iopamidol 300) at a higher rate (3 ml/sec) and gelatin sponge particles instead of gelatin powder for arterial embolization. The success rates for superselective catheterization using conventional (n = 10 procedures) and the improved coaxial catheter systems (n = 7) were 30% and 86%, respectively.

Aberrant right gastric vein directly communicating with left portal vein system. Incidence and implications

In 3 patients with primary hepatic malignancies, a communication between the right gastric vein and the left portal vein system was recognized at angiography. The right gastric vein entered directly into the left lateral portal veins in 2 patients and into the left medial portal veins in one. Portal angio-CT performed in one patient demonstrated a specific defect only in the left lateral superior area of the liver, consistent with the segmental opacification of the portal vein branch recognized on the angiogram. This rare communication was seen in 3 (1.5%) of 200 consecutive patients who underwent celiac angiography and is most likely an anomaly in which the right gastric vein directly enters the left portal vein instead of the portal vein trunk. When interpreting a filling defect not associated with a mass lesion on portal angio-CT for hepatic neoplasms or the right gastric vein communicating with the left portal vein system on the angiogram, this particular anomaly should be considered.

Structural differences among guinea pig Fc gamma 1/gamma 2 receptors on macrophages, polymorphonuclear cells, and lymphocytes

Using the cDNA, D-3, coding for Fc gamma 1/gamma 2 receptor of guinea pig macrophages that binds IgG1 and IgG2 (Fc gamma 1/gamma 2R), we examined the cell distribution of this receptor by RNA blot analysis. The Fc gamma 1/gamma 2R mRNA was expressed in polymorphonuclear cells and B cells as well as in macrophages, but not at the detectable level in T cells. The cDNA amplified from RNA of polymorphonuclear cells in the polymerase chain reaction was the same as D-3. The cDNA of B cells was found to have about 140 bp cDNA segment inserted to the cytoplasmic tail of D-3. We found that the cDNA amplified from T cell RNA differed in signal peptide and extracellular domain sequence from cDNAs of other cell types. This cDNA does not seem to be amplified from the mRNAs of contaminating other cell types.

Supersensitivity to tetrodotoxin and lidocaine of anthopleurin-A-treated Na+ channels in crayfish giant axon

Anthopleurin-A produced two distinct responses in crayfish giant axons: depolarization and prolongation of action potentials. The depolarization was prominent at low concentrations of anthopleurin-A, while a remarkable prolongation of the action potential was produced by higher concentrations of anthopleurin-A. Both effects of anthopleurin-A were inhibited by pre- or posttreatment with tetrodotoxin or lidocaine at concentrations which had not effect on the normal sodium channel. The prolongation of the action potential was more sensitive to tetrodotoxin and lidocaine than the depolarization was. These results suggest that sodium channels of the crayfish giant axon are modified by anthopleurin-A in at least two ways, thereby resulting in sensitization to tetrodotoxin and lidocaine.

Novel cardioprotective effects of TYB-3823 on ischemic damage in the working hearts of rats: comparison with lidocaine

The cardioprotective effects of a new antiarrhythmic drug, TYB-3823 [1-(2,6-dimethylphenyl)-dimethylaminoguanidine hydrochloride] were examined in the working hearts of rats and compared with those of lidocaine. Before ischemia, TYB-3823 at 5 x 10(-5) M produced a slight negative inotropic effect, resulting in a decrease in aortic flow and cardiac output. However, at lower concentrations (10(-6) and 10(-5) M), the drug had no significant effect on the functional cardiac parameters before ischemia. Lidocaine at such concentrations also had no effect. Global ischemia for 15 min decreased cardiac function rapidly which only recovered partially, with a delay, after reperfusion in the control hearts. Treatment with TYB-3823 accelerated the time course of recovery during reperfusion markedly, significantly improving functional cardiac parameters. However, lidocaine had little effect on recovery of function. Reperfusion-induced arrhythmia was equipotently inhibited by TYB-3823 and lidocaine. Leakage of cytosolic enzymes (lactate dehydrogenase, creatine phosphokinase and alpha-hydroxybutylic dehydrogenase) during reperfusion was inhibited more effectively by TYB-3823 than lidocaine. Light microscopic and electron microscopic examinations revealed that treatment with TYB-3823 protected against the histological damage induced by ischemia, such as hyaline degeneration of myocardium, absence of cross-striation and swelling of mitochondria. These results suggest that, unlike lidocaine, TYB-3823 causes a novel cardioprotective effect through unknown mechanisms in addition to its antiarrhythmic action.

Electrophysiological and mechanical effects of calcitonin gene-related peptide on guinea-pig atria

1. The effects of calcitonin gene-related peptide (CGRP) on mechanical and electrophysiological responses were studied in the guinea-pig atrial muscle preparations and in single cells. 2. CGRP (greater than 10(-9) M) enhanced the twitch contraction in a concentration-dependent manner in electrically driven left atria and increased heart rate in spontaneously beating right atria. The positive inotropic and chronotropic effects of CGRP were not inhibited by propranolol but were attenuated by reduction of the calcium concentration in the bathing medium. 3. In single left atrial cells, CGRP slightly hyperpolarized the resting potential but did not affect the other action potential parameters significantly. 4. Under whole-cell voltage-clamp conditions, CGRP increased the calcium inward current. The peptide also increased the steady inward current elicited by hyperpolarization and the late outward current by depolarization. 5. These results suggest that CGRP may produce the positive inotropic and presumably chronotropic effects by increasing calcium inward current. CGRP also increases the potassium permeability. Such effects on ionic currents may not produce any apparent change in the action potential conformation, due to their opposite directional actions and relatively weak potencies.