Changes of beta-1,4-N-acetylglucosaminyltransferase III (GnT-III) in patients with leukaemia

Changes in the activity and transcription of UDP-N-acetylglucosamine: beta-D-mannoside beta-1,4-N-acetylglucosaminyl-transferase III (GnT-III: EC 2.4.1.144) were investigated in haematological malignancies. GnT-III activity was elevated in patients with chronic myelogeneous leukaemia in blast crisis (CML-BC) and patients with multiple myeloma (MM); whereas most of the normal healthy subjects and patients with other haematological malignancies, including CML in its chronic phase, showed negligible activity. The GnT-III transcript of leukaemic cells from various haematological diseases showed a single band with a similar size. The ratio of GnT-III activity per normalized transcript in CML-BC was considerably higher than in the other conditions, which provided the possibility that in CML-BC the transcript or the enzyme protein might be more stable, or that a post-translational modification of the enzyme might enhance its activity. Furthermore, a lectin blot analysis of patient specimens and a lectin fluorescence study of CML cell lines revealed that E4-PHA binding to surface glycoproteins correlated with GnT-III activity, indicating that more bisecting GlcNAc was added to these glycoproteins, catalysed by elevated GnT-III in CML-BC.

Thyroid stimulating antibody in sera of Graves' ophthalmopathy patients as a possible marker for predicting the efficacy of methylprednisolone pulse therapy

Nine patients with Graves' ophthalmopathy (GO) were treated with intravenous methylprednisolone pulse therapy and followed up by ophthalmological assessment, magnetic resonance imaging, and thyroid-associated autoantibody (thyroid stimulating antibody (TSAb), TSH binding inhibitor immunoglobulins (TBII), and anti-eye muscle antibody (EMAb)). Ophthalmological assessment was performed by the ophthalmopathy index (OI) which was made on the basis of the system recommended by the American Thyroid Association Committee. EMAb was expressed as the ratio of density of the 64 kDa band of eye muscle membrane to that of 92 kDa non-specific band found with all normal sera when assessed by western blotting. Five patients with mild ophthalmopathy (OI < 4) did not show progressive improvement in OI. Three of 4 patients with severe eye disease (OI > 4) showed a progressive and distinct improvement in OI. These 3 patients had high TSAb levels before methylprednisolone pulse therapy. One patient with severe ophthalmopathy did not respond to this pulse therapy; this patient's TSAb was negative. A significant positive correlation was observed between the activity of TSAb before treatment and the improvement in OI (delta OI) (r = 0.86, P < 0.01, n = 9). The relationship between delta OI and EMAb did not reach significance. These results suggest that TSAb in sera of GO patients can be a useful marker for predicting the efficacy of methylprednisolone pulse therapy.

Assessment of platelet cytosolic concentration of free magnesium in healthy subjects

We measured basal cytosolic concentration of free Mg2+ ([Mg2+]i) in platelets from 30 healthy volunteers by using mag-fura-2, a new fluorescent Mg2+ indicator. The mean [Mg2+]i was 381 +/- 22 mumol/L, with values ranging from 226 to 771 mumol/L. The day-to-day intrasubject coefficient of variation was relatively small (3.6%). [Mg2+]i was significantly higher in men than in women (430 +/- 38 vs 332 +/- 17 mumol/L, p < 0.03), and was not correlated with age. There was no significant relation between platelet [Mg2+]i and serum total Mg concentration. The results indicate that the gender but not age may decide intracellular Mg2+ status. In addition, the mechanisms that regulate [Mg2+]i may be independent of those that influence the extracellular concentration of Mg.

Urinary excretion of free dopamine and digoxinlike substances correlates with endogenous secretion of insulin in normotensive adults, but not in hypertensive subjects

We investigated whether urinary excretion of free dopamine is related with the humoral factors which affect Na+, K+ ATPase activity in the kidneys. Subjects were 51 adults admitted in a hospital without renal insufficiency: they were divided into normotensive (n = 36, 60 +/- 3 years old, 122 +/- 3/73 +/- 2 mmHg) and hypertensive groups (n = 15, 65 +/- 5 years old, 157 +/- 6/91 +/- 2 mmHg). Urinary excretion of free dopamine was significantly and positively correlated with urinary excretion of C-peptide immunoreactivity of insulin (CPR) (r = 0.451, p = 0.014) in normotensive subjects, but not in hypertensive subjects (r = 0.155, p = 0.668). Urinary excretion of endogenous digoxinlike substances (EDLS) was also significantly and positively correlated with urinary CPR (r = 0.500, p = 0.006) in normotensive subjects, but not in hypertensive subjects (r = 0.275, p = 0.363). In normotensive subjects, urinary excretion of free dopamine and EDLS may be regulated at least in part by insulin secreted endogenously. In hypertensive subjects, however, this regulatory mechanism of the diuretic factors, such as insulin, EDLS and dopamine, is thought to be deranged, which might result in decompensation of a diuretic and antidiuretic balance leading to blood pressure elevation.

Diagnostic significance of dopamine estimation using plasma and urine in patients with adrenal and renal insufficiency, renal transplantation and hypertension

Although free and conjugated dopamine (DA) constitute most of the plasma and urine catecholamine pool, the diagnostic significance of DA estimation for the evaluation of illness is not clear. We evaluated the clinical utility of DA estimation by measuring free and conjugated DA in patients with various illness. Patients with adrenal insufficiency did not show decreases in DA concentrations but did demonstrate reductions in free and conjugated plasma adrenaline (Ad). Patients with established stage of essential hypertension exhibited decreased plasma concentrations of free and conjugated DA, although they were hyperadrenergic. In patients with chronic renal insufficiency and failure, the free DA concentration in the urine decreased depending on the severity of renal impairment. Conversely, plasma concentrations of conjugated DA are higher in patients with chronic renal failure than in normal subjects. The high plasma concentrations of conjugated DA decreased dramatically following hemodialysis and renal transplantation. Urinary free DA excretion increased markedly following renal transplantation. In conclusion, the estimation of the free and conjugated DA in plasma and urine is clinically useful for the diagnosis of adrenal insufficiency, essential hypertension, and renal insufficiency and failure. It also can be used to monitor the effectiveness of hemodialysis and renal transplantation.

The characterization of a novel human adenylyl cyclase which is present in brain and other tissues

We characterized a human cDNA clone which encodes a novel adenylyl cyclase. Data from Southern and Northern blot analysis, and analysis of sequence similarity with a recently cloned mouse adenylyl cyclase (10), indicated that the human adenylyl cyclase was a species variant of type VII adenylyl cyclase. The sequence of the novel human adenylyl cyclase indicated it was a member of the type II adenylyl cyclase family, and we compared the regulatory characteristics of the novel human enzyme with those of type II adenylyl cyclase. The human type VII and rat type II adenylyl cyclases, expressed in human embryonic kidney 293 cells, were activated by prostaglandin E1 (PGE1), but only type VII was activated by isoproterenol. The stimulation of type VII adenylyl cyclase by PGE1 and isoproterenol was attenuated by pretreatment of the cells with staurosporine. Phorbol 12,13-dibutyrate synergistically enhanced the stimulation of both type VII and type II enzyme activity by PGE1 and by the constitutively active Gs mutant Gs (Q227L). The human type VII adenylyl cyclase activity was unresponsive to capacitatively induced changes in intracellular Ca2+. The functional characteristics of human type VII adenylyl cyclase resemble those of the rat type II enzyme, but the enzymes may respond differently to in vivo phosphorylation conditions. While the mRNA for adenylyl cyclase type II was found in several brain areas, the message for type VII adenylyl cyclase was localized primarily to the cerebellar granule cell layer.

Cerebral ATP-sensitive potassium channels during acute reduction of carotid blood flow

The ATP-sensitive potassium channels (KATP) are activated either by a decrease in intracellular ATP content or by a lowering of the ATP-ADP ratio such as during stroke. We studied the role of cerebral KATP on arterial pressure during acute reduction of cerebral blood flow in 12-week-old male Wistar rats anesthetized with urethane by recording arterial pressure and heart rate continuously. After bilateral ligation of the common carotid arteries, glibenclamide, a specific blocker of KATP, was injected intracerebroventricularly into the cerebral lateral ventricle. Glibenclamide elicited a sustained vasopressor response in a dose-dependent manner in rats with bilateral carotid artery ligation (10 nmol, +15 +/- 2 mm Hg; 1 nmol, +5 +/- 1 mm Hg, P < .01 versus vehicle), but hemodynamic alterations were barely recorded with glibenclamide in sham-operated control rats. The abdominal sympathetic discharge was not increased significantly enough to explain the pressor mechanism. Similarly, pretreatments with intravenous injections of bunazosin, an alpha 1-adrenoceptor antagonist, did not affect the pressor response of intracerebroventricular glibenclamide. To investigate the vasopressor mechanism further, we measured plasma and pituitary concentrations of arginine vasopressin and determined the effects of vasopressin receptor antagonists. The intracerebroventricular injections of glibenclamide significantly increased the plasma concentration of vasopressin (P < .05) and significantly decreased the pituitary concentration of vasopressin (P < .05) in rats with bilateral carotid artery ligation. Intravenous pretreatment with the vasopressin V1 receptor antagonist OPC-21268 abolished the vasopressor response to intracerebroventricular glibenclamide (+16 +/- 2 versus +1 +/- 1 mm Hg, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Prolonged survival of mice with human gastric cancer treated with an anti-c-ErbB-2 monoclonal antibody

A monoclonal antibody (MAb), 4D5, specifically recognising an extracellular epitope of the c-ErbB-2 protein, inhibited the growth of human gastric cancer overexpressing c-ErbB-2 severe combined immunodeficient (SCID) mice. This antibody also reduced the mass of established tumours xenografted into SCID mice, whereas gastric cancer not expressing c-ErbB-2 exhibited no regression in response to 4D5 treatment. In addition, administration of 4D5 prevented colonisation of cancer cells and prolonged the survival of host SCID mice inoculated i.v. with c-ErbB-2-overexpressing tumour cells. This is the first reported study to show that treatment with a single antibody specific to c-ErbB-2 prolongs the survival of host SCID mice bearing xenotransplanted tumours.

Differential mechanism of peptide YY and neuropeptide Y in inhibiting motility of guinea-pig colon

The effect of peptide YY on contractility, acetylcholine release and noradrenaline release was examined in the isolated guinea-pig colon, and findings were compared with those for neuropeptide Y. Peptide YY and neuropeptide Y inhibited the twitch contractions mediated by the stimulation of cholinergic neurons. Peptide YY, neuropeptide Y, [Leu31,Pro34]neuropeptide Y and neuropeptide Y-(13-36) inhibited the electrically stimulated release of acetylcholine. Neuropeptide Y, but not peptide YY, inhibited the high K(+)-stimulated tetrodotoxin-resistant release of acetylcholine, while the inhibitory effect of neuropeptide Y disappeared after treatment with yohimbine. Neuropeptide Y, but not peptide YY or neuropeptide Y analogues, evoked the release of noradrenaline. After desensitization to the effects of neuropeptide Y, peptide YY inhibited electrically stimulated acetylcholine release. Thus, peptide YY inhibits acetylcholine release through stimulation of a receptor, distinct from the site of action of neuropeptide Y, located on cholinergic neurons as well as the neuropeptide Y Y1 and Y2 receptors in the guinea-pig colon. Neuropeptide Y inhibits acetylcholine release due to the noradrenaline release mediated by stimulation of a receptor distinct from neuropeptide Y Y1 and Y2 receptors, located on adrenergic neurons.

Incidental Lewy body disease in a patient with REM sleep behavior disorder

We studied an 84-year-old man with a 20-year history of nocturnal violent behavior during sleep, but no other clinically evident neuropsychiatric disorders. Polysomnographic investigations confirmed that he suffered from REM sleep behavior disorder (RBD). Histopathologic examination revealed he had Lewy body disease with a marked decrease of pigmented neurons in the locus ceruleus and substantia nigra. These histologic findings represent the first documented evidence of a loss of brainstem monoaminergic neurons in clinically idiopathic RBD and suggest that Lewy body disease might provide an explanation for idiopathic RBD in the aged.

Expression and secretion of the beta subunit of human chorionic gonadotropin by bladder carcinoma in vivo and in vitro

Expression and secretion of the beta subunit of human chorionic gonadotropin (hCG) by bladder carcinoma cell lines were investigated in vitro and in vivo. As an in vitro study, immunoreactive hCG beta (IR-hCG beta) secreted into the culture media of two bladder transitional cell lines (KoTCC-1 and HT-1197) was analyzed using three kinds of enzyme immunoassays which were specific for intact hCG, free hCG beta, and beta core fragment (beta-CF). Both of the cell lines were determined to secrete IR-hCG beta into the media, which consisted principally of free hCG beta, but detectable levels of intact hCG and beta-CF were not present in the media. Northern blot analysis revealed that the hCG beta gene was expressed in both KoTCC-1 and HT-1197 cells where the sizes of mRNA from these cells were smaller than those from placental and NJG choriocarcinoma cells. As an in vivo study, distribution of IR-hCG beta was analyzed in the tumor tissues, sera, and urine of the mice and the rats transplanted with KoTCC-1 cells. By the immunohistochemical study, the IR-hCG beta was clearly observed in transitional cell carcinoma cells of the transplanted tumor. High levels of IR-hCG beta were detected in both the serum and urine from the animals, but there were quantitative and qualitative differences between serum and urinary IR-hCG beta. Quantitatively, the concentrations of IR-hCG beta in the urine were consistently much higher than those in the serum. Qualitatively, free hCG beta was exclusively detected in the serum whereas high levels of beta-CF in addition to free hCG beta were found in the urine. Intact hCG could not be detected in the serum and urine. These distributions of IR-hCG beta in the animals transplanted with KoTCC-1 cells were completely analogous to those in a patient with hCG beta-producing bladder carcinoma. The present study shows that the same metabolic pathway of IR-hCG beta is operating in mice and rats as in humans, indicating that IR-hCG beta found in patients with bladder carcinoma originates from the tumor and it may be recognized as a tumor marker when beta-CF is measured in the patient's urine.

[Postoperative interstitial pneumonia in primary lung cancer patients--its causes and management]

Eight patients who developed interstitial pneumonia after surgery for primary lung cancer were reviewed to investigate its causes and the key points in treatment. These patients accounted for 1.8% of 633 operated lung cancer patients at our institution over the last 9 years. Risk factors such as bilateral recurrent laryngeal nerve palsy, preoperative chemoradiotherapy, and extensive mediastinal involvement were present in all of them. Pneumonia developed on the nonoperated side in all patients between the 2nd and 45th postoperative day (mean: 18 days). In most of the patients, faint reticular shadows initially appeared in the lower lobe of the nonoperated lung, rapidly spread to the upper lobe, and finally affected the whole lung. Among these eight patients, the initial five patients died because steroids were only administered after the pneumonia had become widespread, whereas the last three patients received early steroid therapy and were saved. The findings that 1) this pneumonia originated from the lower lobe of the nonoperated lung where blood flow is highest postoperatively, 2) the eosinophil count increased just before the onset of pneumonia, and 3) early steroid therapy and immunosuppressive therapy were effective suggest that an allergic or autoimmune mechanism may play some role in its development. When characteristic reticular shadows appear in the lower lobe on the nonoperated side in a lung cancer patient, even if not associated with any symptoms, an early diagnosis of interstitial pneumonia and initiation of steroid therapy is mandatory to ensure survival.

Bioactivity of thyrotropin (TSH) in patients with central hypothyroidism: comparison between in vivo 3,5,3'-triiodothyronine response to TSH and in vitro bioactivity of TSH

To investigate the cause(s) of central hypothyroidism with normal or elevated TSH concentrations, we evaluated the bioactivity of serum TSH as well as pituitary and thyroid function. Seven hypothyroid patients had documented deficiencies of anterior pituitary hormones other than TSH. Basal TSH concentrations ranged from 2.2-14.8 microU/mL. Six patients had low T4 and free T4 concentrations; the remaining patient had a low free T4 and a low normal T4 level with an elevated TSH concentration of 14.4 microU/mL. The mean increment in TSH 30, 60, and 90 min after TRH administration (mean delta TSH) in these patients was 13.5 +/- 9.1 microU/mL (mean +/- SD), which was not significantly different from the value in controls (9.2 +/- 3.5 microU/mL). However, the ratio of the T3 increment at 120 min (delta T3) to mean delta TSH (delta T3/mean delta TSH) in patients was 53.9 +/- 29.3 ng/microU, significantly lower than the control value of 239.5 +/- 97.5 ng/microU (P < 0.01), suggesting that the thyroid response to endogenous TSH was blunted. The serum T4 concentration correlated with the mean delta TSH in these patients (r = 0.78; P < 0.05), suggesting that hypothyroidism is dependent on conserved pituitary function. The mean bioactivity to immunoreactivity ratio of basal TSH in patients was 0.97 +/- 0.27 and was not significantly different from the normal value of 1.05 +/- 0.22. One of the two patients with high basal TSH (> 10 microU/mL) had a ratio of 0.59, which is just below the mean +/- SD of normal subjects (0.61), suggesting that most patients had normal TSH bioactivity in vitro. Our findings suggest that in vivo bioactivity of TSH is decreased because of a pituitary disorder, but in vitro bioactivity of TSH is variable in patients with central hypothyroidism.

Comparison of secretion pattern between A-type and B-type natriuretic peptides in patients with old myocardial infarction

OBJECTIVES

The present study was designed to compare the secretion patterns of two cardiac hormones--A-type (atrial) and B-type (brain) natriuretic peptides--from the ventricles in patients with old myocardial infarction.

BACKGROUND

Plasma levels of these two natriuretic peptides are increased, and their secretion from the ventricles is augmented, in patients with congestive heart failure.

METHODS

We measured the plasma levels of these two types of natriuretic peptides at the aortic root and the anterior interventricular vein in 42 patients with old myocardial infarction (anterior in 22 and inferior in 20) and 18 control subjects.

RESULTS

The difference between the plasma levels of both A- and B-type natriuretic peptide in the anterior interventricular vein and aortic root was significantly greater in the groups with anterior and inferior infarction than in the control group (A-type [mean +/- SD] 380 +/- 290 and 247 +/- 205 pg/ml in the infarction groups vs. 11 +/- 14 pg/ml; B-type 497 +/- 445 and 75 +/- 73 pg/ml vs. 23 +/- 16 pg/ml, respectively). The difference between the plasma levels of each peptide at the anterior interventricular vein and aortic root had a significant negative linear correlation with left ventricular ejection fraction in both groups with infarction. The slope of the regression line of the arteriovenous difference of B-type natriuretic peptide at the anterior interventricular vein was significantly steeper in the anterior than in the inferior infarction group (left ventricular ejection fraction -12.801 vs. -1.891, p < 0.01).

CONCLUSIONS

These results indicate that 1) the secretion of A- and B-type natriuretic peptide from the left ventricular increases in proportion to the severity of left ventricular dysfunction, and 2) secretion of B-type natriuretic peptide is much greater from the infarct than from the noninfarct region, suggesting that the regional ventricular wall stretch caused by infarction strongly stimulates secretion of B-type natriuretic peptide.

Systemic magnesium deficiency disclosed by magnesium loading test in patients with essential hypertension

The present study was designed to determine whether magnesium (Mg) deficiency is present in patients with essential hypertension. We measured the retention of an intravenously administered Mg load (0.2 mmol/kg MgSO4 over 4 h), and serum and erythrocyte Mg concentrations in 17 inpatients with essential hypertension and in 15 normotensive controls. There was no significant difference between the two groups in erythrocyte Mg concentration (normotensives vs., hypertensives: 2.0 +/- 0.5 vs. 2.1 +/- 0.4 mmol/l cells), serum Mg concentration (normotensives vs. hypertensive: 2.1 +/- 0.2 vs. 2.1 +/- 0.2 mg/dl), or in urinary Mg excretion (normotensives vs. hypertensives: 65.8 +/- 25.5 vs. 73.7 +/- 26.7 mg/day). However, Mg retention was significantly higher in hypertensives than in normotensives (normotensives vs. hypertensives: 31.8 +/- 12.1 vs. 41.9 +/- 13.3%). These results suggest that a systemic Mg deficiency, which is undectectable by serum or erythrocyte Mg determination, may exist in patients with essential hypertension.

Angiotensin II inhibition of L-type Ca2+ current in sinoatrial node cells of rabbits

The actions of angiotensin II (ANG II) were examined in the spontaneously active cells isolated from the rabbit sinoatrial node, using the nystatin-permeabilized, whole cell, patch-clamp method. At 30 nM, ANG II significantly lowered the spontaneous firing rate of the action potentials from 212 +/- 21 to 172 +/- 32 beats/min, with a concomitant reduction in the action potential amplitude. The voltage-clamp experiments showed that ANG II inhibited the L-type Ca2+ current (ICa) with a dissociation constant (Kd) of approximately 4 nM and a maximal inhibition of 30%. The inhibition was blocked by an AT1-receptor antagonist CV11974. Acetylcholine (ACh) at 10 microM reduced the ICa by 42 +/- 12%, and ANG II did not cause any further inhibition in the presence of ACh. At 100 nM, ANG II reduced the ICa by only 12% in the presence of 2 microM isoproterenol, and a similar inhibition was observed with 0.1 microM ACh. ANG II did not affect the dibutyryl adenosine 3',5'-cyclic monophosphate-stimulated ICa. Protein kinase C activator 12-O-tetra-decanoylphorbol-13-acetate did not mimic ANG II in the effects on ICa, and preincubation of the cells with calphostin C, a protein kinase C inhibitor, did not attenuate the ANG II effect. ANG II exerts a negative chronotropic effect in the pacemaker cells as its direct action through a pathway involving adenosine 3',5'-cyclic monophosphate-dependent protein kinase.

High expression of UDP-N-acetylglucosamine: beta-D mannoside beta-1,4-N-acetylglucosaminyltransferase III (GnT-III) in chronic myelogenous leukemia in blast crisis

The activity and mRNA expression of UDP-N-acetylglucosamine: beta-D mannoside beta-1,4-N-acetylglucosaminyl transferase III (GnT-III: EC 2.4.1.144) were investigated in hematological malignancies. GnT-III activity was elevated in patients with chronic myelogenous leukemia (CML) in blast crisis and patients with multiple myeloma (MM), as compared to normal healthy subjects and patients with other hematological malignancies including CML in chronic phase. The GnT-III transcript was the same size in leukemic cells from various hematological diseases and cell lines, while expression of the transcript was not found to correlate significantly with enzyme activity, implying that post-translational modification might regulate the activity of GnT-III. Southern-blot analysis showed no significant variation in the structure and position of the GnT-III genome, indicating that the gene is present as a single copy without isoforms. Furthermore, analyses by immunoprecipitation and Western blot revealed that high GnT-III activity in KU812 cell, a CML cell line, resulted in an increase in E4-PHA binding to CD45, a major surface glycoprotein of the leukocyte, indicating that more bisecting GlcNAc was added to CD45 catalyzed by elevated GnT-III.

Cell spreading in Colo 201 by staurosporin is alpha 3 beta 1 integrin-mediated with tyrosine phosphorylation of Src and tensin

Staurosporin, a broad-spectrum kinase inhibitor, induced cell spreading in a human colon cancer cell line, Colo 201. On collagen and laminin, cell spreading was induced in more than 90% of the cells and was dependent on very late activation antigen-3, as shown by an antibody inhibition assay. Cell spreading required divalent cations and showed the order of preference Mn2+ > Mg2+ > Ca2+. On fibronectin, only about 30% of the cells were observed to spread, and spreading occurred via a non-integrin, RGD-independent pathway. Staurosporin-induced spreading was inhibited by treatment with tyrosine kinase inhibitors herbimycin A and methyl 2,5-dihydroxycinnamate. Despite the presence of staurosporin, seven proteins (220, 175, 150, 98, 62, 58, and 45 kDa) showed increased levels of tyrosine phosphorylation in association with cell adhesion. Two of these (58 and 220 kDa) were identified by immunoprecipitation as Src product and tensin, respectively. Flow cytometric analysis showed that the Colo 201 cells expressed the alpha 2, alpha 3, alpha 6, and beta 1 chains of integrin, but expression of these chains was not influenced by staurosporin. Immunofluorescence microscopy revealed that the alpha 3 chain, diffusely expressed on the cell surface in the absence of staurosporin, was concentrated at focal adhesion plaques after staurosporin treatment. Neither alpha 2 nor alpha 6 was focalized by the treatment.

Quantitative changes in G proteins do not mediate ethanol-induced downregulation of adenylyl cyclase in mouse cerebral cortex

Our prior work, and the work of others, demonstrated that chronic administration of ethanol to cells in culture or to mice resulted in decreased responsiveness of adenylyl cyclase (EC4.6.1.1) to a number of stimulatory agents. In this study, we substantiated the ethanol-induced changes in cerebral cortical adenylyl cyclase activity in alcohol-tolerant and alcohol-dependent mice, and we examined whether chronic ethanol treatment of mice altered the quantity of heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins) in cerebral cortex and other mouse brain areas. Amounts of various G protein subunits--including the alpha subunits of GS (GS alpha), Gi alpha 1-3, G(o) alpha, and beta subunits--were examined by Western blot analysis. There was no change in quantity of these G protein subunits in cerebral cortex, hippocampus, or cerebellum of ethanol-fed mice, compared with controls. In striatum of ethanol-fed mice, small increases in Gi alpha 1 and G(o) alpha were observed, but these changes could not explain the ethanol-induced desensitization of adenylyl cyclase in brain areas such as the cerebral cortex. Forskolin activation of cerebral cortical adenylyl cyclase activity showed two components of activation, with high and low "affinity" for forskolin. Ethanol treatment caused a decrease in the efficacy of forskolin for both components, whereas the EC50 of forskolin for each component did not change. Adenylyl cyclase activity measured in the presence of manganese was also diminished in cortical membranes of ethanol-treated mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of brain (B-type) natriuretic peptide on coronary artery diameter and coronary hemodynamic variables in humans: comparison with effects on systemic hemodynamic variables

OBJECTIVES

This study attempted to clarify the effects of human brain (B-type) natriuretic peptide on coronary artery diameter and coronary vascular resistance in humans.

BACKGROUND

Brain natriuretic peptide induces vasodilation in systemic circulation by activating particulate guanylate cyclase of the vascular smooth muscle.

METHODS

In 13 patients with normal coronary arteries and left ventricular function, brain natriuretic peptide was infused at 0.5 microgram/kg body weight per min for 4 min into the left main coronary artery (six patients, Group A) or into the pulmonary artery (seven patients, Group B). Systemic hemodynamic variables and coronary sinus blood flow were measured before and after the infusion. The lumen diameter of the left coronary artery was quantitatively measured.

RESULTS

In both groups, brain natriuretic peptide significantly increased heart rate and decreased mean arterial pressure. Rate-pressure product remained unchanged in both groups. Brain natriuretic peptide decreased systemic vascular resistance index significantly in both groups (both p < 0.01 vs. baseline), and there was no difference in the effect between the groups. Brain natriuretic peptide decreased coronary vascular resistance in Group A (p < 0.01 vs. baseline) but did not affect coronary vascular resistance in Group B (p < 0.01 vs. Group A). The lumen diameters of the proximal and distal segments of the left coronary artery were increased significantly after brain natriuretic peptide in both groups. After infusion of brain natriuretic peptide, mean plasma level of brain natriuretic peptide in the coronary sinus increased from 36 to 130,411 pg/ml in Group A and from 64 to 12,329 pg/ml in Group B.

CONCLUSIONS

Brain natriuretic peptide shows a vasodilator effect on the coronary artery system in humans. However, the effect does not appear uniformly but is seen preferentially in the epicardial coronary artery. The sensitivity of the coronary resistance vessels to brain natriuretic peptide is low compared with that of the resistance vessels of the systemic circulation.