Comparison of the coat protein genes of five fish nodaviruses, the causative agents of viral nervous necrosis in marine fish

Striped jack nervous necrosis virus (SJNNV), a nodavirus, is the causative agent of viral nervous necrosis (VNN) in larval striped jack fish. In the present study, the SJNNV coat protein gene was sequenced and compared with that of four known insect nodaviruses and with four other fish nodaviruses causing VNN. The SJNNV coat protein gene was 1410 bases in length and contained a single ORF of 1023 bases encoding a protein of 340 amino acids. The sequence similarities between the coat protein gene of SJNNV and four insect nodaviruses were 28.6% or less at the nucleotide level and 10.6% or less at the amino acid level. A portion of the coat protein gene from four additional fish VNN viruses was amplified by PCR using primers designed for SJNNV and the amplified fragments (870-876 bases) were sequenced. The sequence similarities among SJNNV and the four VNN viruses were 75.8% or greater at the nucleotide level and 80.9% or greater at the amino acid level. In the fish nodaviruses a highly conserved region of 134 amino acids with sequence similarity of 92.5% or greater was detected. This conserved sequence was not found in the coat protein of insect nodaviruses. These results indicate that the fish nodaviruses that cause VNN are closely related to each other but are quite different from insect nodaviruses.

Enhancement of the binding of triglyceride-rich lipoproteins to the very low density lipoprotein receptor by apolipoprotein E and lipoprotein lipase

The low-density lipoprotein (LDL) receptor plays a crucial role in cholesterol metabolism. A related protein, designated the very low density lipoprotein (VLDL) receptor, that specifically binds apolipoprotein (apo) E has recently been characterized and shown to be expressed in heart, muscle and adipose tissue and the human monocyte-macrophage cell line THP-1. The VLDL receptor binds and internalizes VLDL and intermediate density lipoprotein from Watanabe heritable hyperlipidemic (WHHL) rabbits as well as beta-migrating VLDL from cholesterol-fed rabbits but not LDL from WHHL rabbits. Chinese hamster ovary (CHO) cells transfected with the rabbit VLDL receptor cDNA have now been shown to bind or internalize VLDL (d < 1.006 g/ml) isolated from fasted normolipidemic human subjects with lower affinity than WHHL-VLDL or rabbit beta-VLDL. However, binding and internalization were markedly enhanced when fasted human VLDL was preincubated with either recombinant human apoE (3/3) or lipoprotein lipase (LPL) in CHO cells overexpressing the rabbit or human VLDL receptor. CHO cells transfected with both the rabbit VLDL receptor cDNA and the human LPL cDNA effectively bound, internalized, and degraded fasted human VLDL without pretreatment. Treatment of heparinase reduced the effect of LPL-mediated binding at 4 degrees C, but the inhibitory effect was lower at 37 degrees C. Pseudomonas LPL also enhanced the binding of human fasted VLDL to the VLDL receptor at 37 degrees C in CHO cells overexpressing the human VLDL receptor. Taken together, LPL causes the enhancement of triglyceride-rich lipoproteins binding to the VLDL receptor via both the formation of bridge between lipoproteins and heparan sulfate proteoglycans and its lipolytic effect. Ligand blot analysis showed that the apparent molecular mass of the VLDL receptor is 118 kDa, which is smaller than that of the LDL receptor. These results indicate that the VLDL receptor recognizes both triglyceride-rich lipoproteins that are also relatively rich in apoE, as well as the remnants of triglyceride-rich lipoproteins after catabolism and the interaction with heparan sulfate proteoglycans by LPL. The VLDL receptor may thus function as a receptor for remnants of triglyceride-rich lipoproteins in extrahepatic tissues.

[Diagnostic applications of laboratory tests in primary medical practice endocrine disorders]

The diagnostic steps for endocrine disorders have been complex mainly because abnormalities in more than one endocrine organ often coexist in a single patient. Also, endocrine disorders are diverse and it is hard to cover them all here. I have defined the initial tests and additional tests to confirm the initial diagnosis in the two endocrinopathies; Basedow's disease as a representative of relatively common diseases and pheochromocytoma as an example of uncommon disorders. Abnormalities in routine laboratory test results such as hypocholesterolemia in hyperthyroidism can provide some clues to the diagnosis of endocrine disorders. Initial tests for suspected Basedow's disease would be free or total T4 and TSH. In addition, free or total T3 and TRAb will be included under some circumstances. Although uncommon, the diagnosis of pheochromocytoma should be considered in patients with paroxysmal symptoms and in hypertensive patients not responding well to conventional therapy. As an initial step for screening this disorder, I would recommend to determine 24h urinary catecholamine levels (adrenaline, noradrenaline and metanephrine). When abnormally high test results have been obtained, the tumor must be located in order to facilitate its surgical removal. CT and MIBG scintigraphy are of value in identifying these tumors. When localization of tumors by imaging diagnosis is unsuccessful, analysis of blood samples obtained via percutaneous venous catheterization will help establish the diagnosis. These guidelines are still preliminary and are open for critical discussion.

[Expression of mRNAs coding for catecholamine synthesizing enzymes in human adrenal pheochromocytoma]

Pheochromocytomas synthesize and release catecholamines, which subsequently are related to various clinical manifestations of the disease. However, pheochromocytomas are not innervated and the catecholamine release and synthesis are not initiated by neural impulses. It is still unknown how catecholamine synthesis is regulated in pheochromocytomas. As a first step toward understanding the molecular mechanisms by which catecholamine synthesis is controlled in the tumor, we measured the levels of mRNA coding for the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH) and catecholamines in 6 pheochromocytomas and 2 normal adrenal glands. The TH mRNA level was overexpressed and the catecholamine contents were high in 4 out of 6 pheochromocytomas. There was a close correlation between the TH mRNA level and the catecholamines content in the tumors. We also examined the gene expression of the messengers of other catecholamine synthesizing enzymes, dopamine beta-hydroxylase (DBH) and aromatic 1-amino acid decarboxylase (AADC) in pheochromocytomas. The expression of these genes was in parallel with that of TH mRNA in the tumors. These findings indicate that catecholamine overproduction in pheochromocytomas is mediated by the overexpression of genes coding for catecholamines synthesizing enzymes, TH, DBH, and AADC.

Increased nitric oxide biosynthesis in leukotoxin,9,10-epoxy-12-octadecenoate injured lung

We measured effluent nitric oxide levels using a chemiluminescence method from leukotoxin (Lx, a linoleate epoxide) injured isolated rat lungs perfused with physiological salt solution. Nitric oxide production from Lx-injured lung promptly increased and lasted for 20 min. Pretreatment with NG-monomethyl-L-arginine (LNMMA) significantly suppressed Lx-induced production of nitric oxide. Effluent from control lungs showed trace levels of nitric oxide. The wet to dry lung weight (WLW/DLW) after termination of the experiments was significantly elevated in Lx-treated lungs compared with that of LNMMA pretreated lungs or control lungs. There was a correlation between nitric oxide levels (at 10 min) and lung edema (WLW/DLW). Thus, nitric oxide plays a role in the pathogenesis of Lx-induced lung injury.

A case of achondroplasia with downward displacement of the brain stem

We report a case of achondroplasia with downward displacement of the brain stem. Although upward displacement and anterior angulation deformity of the brain stem are common findings in achondroplasia, they were not observed in this case, because of a coexistent Chiari malformation.

Autocrine production of endothelin-1 participates in the glucocorticoid-induced Ca2+ influx into vascular smooth muscle cells

We determined whether endothelin-1 (ET-1) is associated with glucocorticoid-induced Ca2+ influx into vascular smooth muscle cells by examining the effects of the ETA receptor antagonist FR139317 on dexamethasone-induced 45Ca2+ uptake and dihydropyridine binding by rat A7r5 cells. FR139317 inhibited the dexamethasone-induced 45Ca2+ uptake and [methyl-3H]PN 200-110 binding in a dose-dependent manner. Slot blot analysis revealed that dexamethasone increased protein kinase C-alpha in A7r5 cells and that this effect was also abolished by FR139317. Dexamethasone stimulated the release of immunoreactive endothelin-1 from A7r5 cells into the culture medium. These results suggest that endothelin participates in the glucocorticoid-induced Ca2+ influx through dihydropyridine-sensitive channels in an autocrine manner, possibly linked to the activation of protein kinase C-alpha.

Determination of spin parameters reflected in the nuclear magnetic resonance powder patterns for two equivalent 31P nuclei in Lawesson's reagent

The nuclear magnetic resonance (NMR) powder patterns observed for the 31P spin pair in Lawesson's reagent (1) were analyzed. Using an efficient procedure, wide ranges of the spin parameters were examined to determine whether they might reproduce the experimental one-dimensional (1D) spectrum of the present A2 spin system. It was demonstrated that the parameters were not uniquely determined from the 1D powder pattern only, but a significant reduction of their uncertainties was realized using the two-dimensional (2D) powder pattern. The molecular structure of 1 was discussed in terms of the refined spin parameters.

Lipid accumulation and foam cell formation in Chinese hamster ovary cells overexpressing very low density lipoprotein receptor

The rabbit very low density lipoprotein receptor gene was introduced into LDL receptor-negative Chinese hamster ovary cells (ldl-A7). Incubation of the transfected cells with rabbit beta-VLDL (5 to 8 micrograms protein/ml), for 6 days, induced foam cell formation. The cells accumulated lipid droplets visualized by oil red-O staining; the cellular cholesteryl ester and triglyceride content increased two- to threefold. [3H]Oleate incorporation into cholesteryl [3H]oleate was stimulated threefold by incubation of cells with beta-VLDL (20 micrograms protein/ml). Northern blot analysis revealed the presence of VLDL receptor mRNA in rabbit resident alveolar macrophages. Incubation of the macrophages with beta-VLDL (20 micrograms protein/ml) for 24 hours induced foam cell formation but had virtually no effect on VLDL receptor mRNA abundance. These results suggest that the VLDL receptor on macrophages may play an important role in foam cell formation.

Relation of angiographically defined coronary artery disease and plasma concentrations of insulin, lipid, and apolipoprotein in normolipidemic subjects with varying degrees of glucose tolerance

We investigated the association between hyperinsulinemia and changes in lipid, lipoprotein, and apolipoprotein that would increase the risk of coronary artery disease (CAD) independent of glucose tolerance. A coronary angiogram was recorded in 127 male subjects, including 41 with normal glucose tolerance, 41 with impaired glucose tolerance, and 45 with non-insulin-dependent diabetes mellitus (NIDDM). Subjects were divided into 2 groups according to results: the group with CAD (n = 94) and the group with normal coronary arteries (n = 33). All subjects were normolipidemic (total cholesterol < 230 mg/dl and triglycerides < 150 mg/dl). The CAD group had a significantly lower plasma level of high-density lipoprotein (HDL) cholesterol and apolipoprotein A-I (apo A-I) and a higher level of apolipoprotein B (apo B) than the normal group with normal glucose tolerance. In considering subjects with impaired glucose tolerance or NIDDM, the CAD group had a significantly lower plasma level of HDL cholesterol and apo A-I and a significantly higher plasma level of total cholesterol, triglycerides, and apo B than the normal group. In each of the subjects with normal and impaired glucose tolerance, and NIDDM, the elevation of plasma insulin concentration during both the complete test period and the early phase of an oral glucose challenge was significantly higher in the CAD than in the normal group. In all subjects, graded reductions in HDL cholesterol and apo A-I and graded increases in plasma total cholesterol, triglycerides, and apo B were observed with increasing tertiles of the postglucose challenge measurements of insulinemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of intrahepatic portal-systemic shunting on hepatic ammonia extraction in patients with cirrhosis

Increased plasma ammonia levels in patients with advanced cirrhosis have been attributed to reduced conversion of enteric ammonia to urea by the diseased liver and to entry of enteric ammonia into systemic circulation by way of portal-systemic shunts. Because single-pass extraction is high for portal venous ammonia, reduction of portal blood supply to hepatocytes may have detrimental effects on the hepatic extraction of ammonia. To assess how the development of intrahepatic portal-systemic shunts alters hepatic ammonia metabolism, we determined portal and hepatic venous ammonia levels along with measurements of intrahepatic portal-systemic shunts using 99mTc-macroaggregated albumin in 46 patients with portal hypertension. Hepatic venous ammonia levels in the groups of patients with idiopathic portal hypertension, Child class A cirrhosis and Child class B or C cirrhosis were 36 +/- 17, 75 +/- 26 and 93 +/- 52 micrograms/dl, respectively, in increasing order, and portal venous ammonia extraction rates as calculated with the equation (portal venous ammonia-hepatic venous ammonia)/portal venous ammonia x 100% were decreased in the same order (77% +/- 14%, 50% +/- 21%, 40% +/- 25%, respectively). Furthermore, we noted a significant negative correlation between the intrahepatic shunt indexes as calculated by counts per minute in lungs/counts per minute in lungs and liver x 100% and the ammonia extraction rates. It was noteworthy that among Child class C patients, the ammonia extraction rates were significantly lower in patients with high intrahepatic shunt indexes than in those with low shunt indexes. These results demonstrate a significant direct relationship between hepatic ammonia extraction rates and intrahepatic shunting in cirrhosis.

Diltiazem inhibits DNA synthesis and Ca2+ uptake induced by insulin, IGF-I, and PDGF in vascular smooth muscle cells

Proliferation of vascular smooth muscle cells (VSMC) has been shown to play a key role in the atherosclerotic lesions. It has been demonstrated that serum-derived peptidic growth factors, such as insulin, platelet-derived growth factor (PDGF), or epidermal growth factor (EGF), provide mitogenic signals in VSMC and that the interplay of Ca2+ and other messengers is necessary for triggering proliferation. Since Ca2+ channel blockers act on the voltage-dependent Ca2+ channel to inhibit Ca2+ influx, it is conceivable that they affect the proliferative action of growth factors. In this study we have evaluated the effects of diltiazem, a 1,5-benzothiazepine-derived Ca2+ channel blocker, on [3H]thymidine incorporation into DNA stimulated by insulin, insulinlike growth factor I (IGF-I), or PDGF in cultured VSMC from rat aorta. We have also investigated the effects of insulin, IGF-I, and PDGF on Ca2+ uptake in VSMC. After exposure to insulin (10(-10) to 8 x 10(-6) M) or IGF-I (10(-10) to 10(-7) M) for 48 hours, VSMC incorporated [3H]thymidine to 200-280% of maximum (with insulin or IGF-I alone) compared to control. The effect of IGF-I was approximately 10-100 times more potent than that of insulin. PDGF (0.5-15 ng/ml) also induced an increase in [3H]thymidine incorporation into DNA of VSMC. Additivity is observed between PDGF with insulin or IGF-I, but not between insulin and IGF-I. Sixty minute treatment with insulin (5 x 10(-8) to 10(-6) M), IGF-I (10(-8) to 10(-6) M), or PDGF (1.0-15.0 ng/ml) increased the unidirectional 45Ca2+ uptake during a 5 minute period.(ABSTRACT TRUNCATED AT 250 WORDS)

[HDL receptor]

Epidemiological studies have demonstrated that high density lipoprotein cholesterol (HDL-C) is inversely related to the incidence of coronary heart disease morbidity and mortality. In the present paper, we summarized the recently published data on HDL receptor, reverse cholesterol transport, and antiatherogenic effect of HDL particle. Several investigators have reported the apparent molecular weight of HDL binding protein using ligand blotting by radiolabeled HDL and immunoblotting by antibody against the purified binding protein. These results, however, were not consistent among the data reported from several laboratories. In 1992 a cDNA of HDL binding protein (HBP) was isolated from a human fibroblast and a human erythroleukemia cell cDNA library but it does not contain a classical hydrophobic membranes spanning domain. At present, it is reasonable to assume that HBP is different structurally and functionally from a classical plasma membrane receptor. We hope putative HDL receptor will be isolated, characterized and its cDNA will be cloned in the near future. It has been postulated that there are four functional steps in the pathway of reverse cholesterol transport. The main step is CETP-mediated transfer of cholesteryl esters from HDL to the VLDL/LDL fraction. Recent development of molecular biological techniques enable us to make a animal model over expressing apolipoprotein A-I or A-II, namely a transgenic mouse. These models indicated that apolipoprotein A-I has an antiatherogenic effect in vivo but apolipoprotein A-II does not.

Increase in neutral cholesteryl ester hydrolase activity produced by extralysosomal hydrolysis of high-density lipoprotein cholesteryl esters in rat hepatoma cells (H-35)

The metabolism of high-density lipoprotein-associated cholesteryl esters (HDL-CE) in liver cells is not well understood. We studied the possible role of lysosomal and extralysosomal pathways on such metabolism by measuring the uptake and hydrolysis of HDL-CE in H-35 rat hepatoma cells. Incubation of cells with [3H]cholesteryl ester-labeled HDL led to the intracellular accumulation of both 3H-free cholesterol and [3H]cholesteryl ester. The ratio of 3H-free cholesterol/[3H]cholesteryl ester increased with an increase in incubation time even in the presence of chloroquine. Because chloroquine did not inhibit the conversion of cholesteryl ester to free cholesterol, the hydrolysis of HDL-CE may have been catalyzed by an extralysosomal enzyme, perhaps by neutral cholesteryl ester hydrolase (NCEH). When we incubated cells with increasing concentrations of HDL, NCEH activity increased. This increase in enzyme activity was not inhibited by the addition of chloroquine. A complex of dimyristoylphosphatidylcholine (DMPC)/apo HDL/cholesteryl ester enhanced the activity as well as native HDL. Neither the DMPC/apo HDL nor the DMPC/cholesteryl ester complex affected the activity, suggesting that apo HDL may be required for the uptake of HDL-CE. The present study demonstrated that the extralysosomal hydrolysis by NCEH is operating in the metabolism of HDL-CE in hepatoma cells.

A newly identified heterozygous lipoprotein lipase gene mutation (Cys239-->stop/TGC972-->TGA; LPLobama) in a patient with primary type IV hyperlipoproteinemia

We investigated measures for identification of heterozygous lipoprotein lipase (LPL) deficiency in unrelated subjects with primary type IV hyperlipoproteinemia in order to acquire a helpful clue for understanding the correlation between hypertriglyceridemia and the status of being a heterozygous carrier of an LPL gene variant. Identification of heterozygous LPL deficiency was performed by monitoring the immunoreactive LPL mass in postheparin plasma (PHP) using our developed sandwich-enzyme immunoassay technique for first screening. Then, in subjects found to have half or less than half of the control LPL mass value in PHP, the polymerase chain reaction-single strand conformation polymorphism method was used to detect LPL gene aberrations as a second screening. This approach was evaluated as being useful as it succeeded in identifying a subject (proband KD) with heterozygous LPL deficiency. The mutation in the LPL gene of proband KD was newly characterized as a nucleotide C972 to A transversion in exon 6, resulting in substitution of a premature termination codon (TGA) for Cys239 (TGC). This nonsense mutation, designated as LPLobama, creates an MboI restriction site and eliminates an HgiAI restriction site, and this allows rapid screening of subjects with type IV as well as type I hyperlipoproteinemia for the mutation. The homozygous state for the LPLobama allele resulted in neither detectable LPL activity nor immunoreactive LPL mass in PHP, and this was seen in two of proband KD's siblings.

Pertussis toxin pretreatment enhances catecholamine secretion induced by pituitary adenylate cyclase-activating polypeptide in cultured porcine adrenal medullary chromaffin cells: a possible role of the inositol lipid cascade

We determined how pertussis toxin (PTX) pretreatment alters PACAP-induced catecholamine secretion in cultured porcine adrenal medullary cells. Pretreatment of these cells with PTX (1 ng/ml for 24 h or 10 ng/ml for 6 h) markedly enhanced PACAP-induced catecholamine secretion. PTX pretreatment also produced a small increase in basal secretion and secretion in response to nicotine and carbachol, but the effect of the PACAP-induced secretion was most striking. We examined the role of the phosphoinositol cascade in potentiating the PACAP-induced catecholamine secretion by PTX and found that PACAP-induced accumulation of inositol phosphates in PTX-pretreated cells was significantly greater than that in untreated cells. Furthermore, removal of extracellular Ca2+ and addition of Ca2+ channel blockers inhibited the catecholamine secretion induced by PACAP in PTX-pretreated cells. From these results, we speculate that a PTX-sensitive G-protein tonically inhibits phospholipase C. PTX enhances the PACAP-induced secretion of catecholamine by blocking the action of this inhibitory G-protein.

Extracorporeal shock wave lithotripsy (ESWL) for biliary stones: a nationwide survey in Japan

To assess the current status of extracorporeal shock wave lithotripsy (ESWL) for the treatment of gall-stones in Japan, we conducted a nationwide survey by sending a questionnaire to 251 institutions using this therapy. Replies were obtained from 50 institutions. The use of ESWL was investigated over the period from its introduction up to October 1992. ESWL was performed on 2,760 of 10,058 patients with gallstones (27.4%). The stones were completely pulverized in 1,021 of these 2,760 patients (37.0%). Complete disappearance was limited to single gallstones less than 20 mm in maximum diameter. A comparison in the number of ESWL sessions revealed no significant difference between the patients with and without a good response. Choledocholithiasis was resolved completely in 44.0% of 157 patients who underwent ESWL for this condition and intrahepatic stones were cured in 18.7% of 32 patients. Therefore, ESWL may be a useful form of conservative therapy for biliary calculi.

Divalent metal ion-dependent mitochondrial degradation of unassembled subunits 2 and 3 of cytochrome c oxidase

Intracellular protein degradation plays an important role in maintaining the stoichiometry of the different subunits of an oligomeric enzyme. In a Saccharomyces cerevisiae mutant defective in cytochrome c oxidase subunit 4 encoded in nuclear DNA, mitochondrial-encoded subunits 2 and 3 cannot assemble normally [Dowhan et al. (1985) EMBO J. 4, 179-184]. In this study, we show that those unassembled forms of subunits 2 and 3 in this strain are eliminated rapidly by degradation. Reduction of the intracellular ATP level by inhibiting the glycolytic pathway, or inhibition of the entry of ATP into mitochondria by bongkrekic acid, both of which are expected to reduce the intramitochondrial ATP level in respiratory-deficient cells such as WD1, significantly suppressed the degradation, suggesting that the degradation requires intramitochondrial ATP. The degradation was also inhibited by o-phenanthroline, a membrane-permeable metal chelator, and this inhibitory effect was suppressed by addition of an excess amount of Co2+, Mn2+, or Zn2+, but not by Ca2+ or Mg2+, suggesting a novel metal-dependence of the degradation of unassembled Cox II and Cox III which has not been reported previously for mitochondrial metabolic protein degradation systems. A potential advantage of using this strain for identifying the factor(s) involved by a genetical approach is discussed.

Clinical features of hepatocellular carcinoma in the elderly: a study of 91 patients older than 70 years

In order to determine the clinical features of hepatocellular carcinoma in the elderly, a total of 622 patients with hepatocellular carcinoma, including 91 patients 70 years or older, were retrospectively analysed with reference to their ages at the time of diagnosis. The proportion of females increased and that of hepatitis B surface antigen-positive cases decreased as age increased. Tumour sizes at the time of diagnosis were somewhat smaller in the elderly than in younger patients, whereas clinical stage taking liver function into consideration was similar in the two age groups. The prognosis in the elderly patients was similar to that in the younger ones in a clinical stage-matched comparison. Furthermore, by a multivariate analysis using the Cox proportional hazards model with inclusion of age and other clinical parameters, age was not selected in the final model as an independent predictor for survival. These results indicate that elderly patients with hepatocellular carcinoma have certain clinical features different from those in younger patients and that their prognosis is not necessarily poorer than in the latter.

Effects of diazoxide on norepinephrine-induced vasocontraction and ischemic myocardium in rats

Effects of diazoxide on norepinephrine-induced vasocontraction in vitro and global ischemia-induced lactate accumulation in the myocardial tissue in vivo were studied in rats. Diazoxide produced relaxation of the isolated rat aorta contracted by norepinephrine in a dose dependent manner. The relaxation of the aorta was associated with reduction of intracellular Ca2+ concentration. This reduction may be due either to activation of KATP channels or Na(+)-K+ ATPase, or to both. Global ischemia induced by aorta constriction for 30 min in vivo increased the myocardial tissue level of lactate. Pretreatment with diazoxide (10 mg.kg-1, i.v.) significantly attenuated the accumulation of lactate due to global ischemia. The present study suggests that diazoxide reduces ischemic influence on the myocardium partly through its vasodilatory action.

Effects of chronic diabetes on the responsiveness to endothelin-1 and other agents of rat atria and thoracic aorta

1. Plasma endothelin-1 level as well as plasma lipid and glucose levels was markedly elevated in the rats treated with streptozotocin 8 weeks earlier. 2. Positive inotropic response, which was significantly greater than that in the age-matched control, was produced by endothelin-1 in the left atria isolated from diabetic rats. On the other hand, the contractile response of thoracic aorta to endothelin-1 was conversely attenuated in the diabetic rats. Such contrasting effects of diabetes between the atrial and aortic muscles were observed in the responsiveness to other contractile drugs. Endothelium-dependent relaxation in the thoracic aorta was also significantly attenuated in diabetic rats. However, the basal twitch contraction of left atria, the chronotropic responses to endothelin-1, isoproterenol and carbachol and the relaxation of the aorta by papaverine were not affected by diabetes. 3. These results suggest that the contractile responsiveness of atrial and aortic muscles and the endothelial functions significantly alter during diabetes for 8 weeks.