Quantitative analysis of changes in blood concentrations and 'presumed effect-site concentration' of sevoflurane during one-lung ventilation.

During one-lung ventilation, ventilation-perfusion mismatch decreases the arterial concentration of inhaled anaesthetics due to the arterial-to-venous concentration difference. This study tested the hypothesis that in humans, the 'presumed effect-site concentration' (taken as the mid-point between the arterial and superior jugular venous concentrations) of inhaled anaesthetic falls during one-lung (vs two-lung) ventilation. Four patients scheduled for elective prostatectomy (two-lung ventilation) and four patients for elective thoracotomy (one-lung ventilation) were randomly selected and assigned to receive sevoflurane (vaporiser-dial setting, 1.5%). Sevoflurane concentrations were measured periodically from radial artery and superior jugular vein (via a catheter advanced cephalad from the jugular vein). During one-lung ventilation, the end-expiratory sevoflurane concentration was stable at ∼1.3% but the mean (SD) presumed effect-site concentration declined initially from 58 (6.7) to 43 (4.7) µg.ml(-1) (p=0.011) before slowly recovering. A period of insufficient depth of anaesthesia is thus a risk during one-lung ventilation.

Quantitative differences in GlcNAc:beta1-->3 and GlcNAc:beta1-->4 galactosyltransferase activities between human colonic adenocarcinomas and normal colonic mucosa.

The activities of GlcNAc:beta1-->3 and GlcNAc:beta1->4 galactosyltransferases in normal human colonic mucosa and well or moderately differentiated colonic adenocarcinomas and their enzyme-kinetic characteristics were investigated. After UDP-[3H]galactose and N-linked type monoantennary oligosaccharides GlcNAc beta1-->2Man alpha1-->3(6)Man beta1-->4GlcNAc) had been incubated with microsome fractions prepared from these tissues, the synthesized [3H]galactose-labeled oligosaccharides were analyzed by Ricinus communis agglutinin-I agarose chromatography, Streptococcus 6646K beta-galactosidase, Gal beta1-->4-specific diplococcal beta-galactosidase, and Gal beta1-->3GlcNAc-specific lacto-N-biosidase digestion. The beta-galactosyltransferases from normal mucosa synthesized both type 1 and type 2 chains at comparable levels, whereas those from adenocarcinomas predominantly synthesized type 2 chains. To our knowledge, this is the first quantitative estimation of GlcNAc:beta1-->3 galactosyltransferase activity toward N-linked sugar chains. Furthermore, we compared the two galactosyltransferase activities in 10 normal mucosa and adenocarcinoma samples and found that while there existed similar levels of GlcNAc:beta1-->4 galactosyltransferase activity in normal mucosa and adenocarcinomas, GlcNAc:beta1-->3 galactosyltransferase activity apparently decreased from 0.67 +/- 0.26 (normal mucosa) to 0.18 +/- 0.11 nmol/min/mg of protein (adenocarcinomas). These results are consistent with those of comparative structural studies on N-linked sugar chains of carcinoembryonic antigen and its normal counterparts and suggest that in the process of differentiated carcinogenesis of human colonic tissues, the expression of GlcNAc:beta1-->3 galactosyltransferase is negatively regulated.

Sugar chains of human cord serum alpha-fetoprotein: characteristics of N-linked sugar chains of glycoproteins produced in human liver and hepatocellular carcinomas.

Human serum alpha-fetoprotein (AFP) is elevated in not only hepatocellular carcinoma (HCC) but also benign liver diseases. AFP produced in HCC and benign liver diseases was separated into several isoforms corresponding to different sugar chain structures by several types of lectin affinity electrophoresis, and the HCC-specific AFP isoform was discriminated from those of benign liver diseases. Because a small amount of HCC-specific AFP isoform was detected in cord serum AFP, the whole sugar chain structures of human cord serum AFP were determined, as follows: Neu5Ac alpha 2-->Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->6(Neu5Ac alpha 2 -->6Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->3)Man beta 1-->4R1 and R2, Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->6(Neu5Ac alpha 2-->6Gal beta 1 -->4GlcNAc beta 1-->2Man alpha 1-->3)Man beta 1-->4R1 and R2, and Neu5Ac alpha 2-->3Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->6(Neu5Ac alpha 2 -->6Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->3)Man beta 1-->4R1 and R2 in the ratio of 81.6:8.9:9.5. R1 and R2 denote GlcNAc beta 1-->4GlcNAcOT (subscript OT represents an NaB3H4-reduced oligosaccharide) and GlcNAc beta 1-->4(Fuc alpha 1-->6)GlcNAcOT, respectively, and the ratio between R1 and R2 in the respective fractions was approximately 19:1. In contrast, the sugar chain structure of HCC highly specific AFP isoform was found to comprise a monosialyl-biantennary sugar chain with additional fucosylation of the proximal N-acetylglucosamine. Fucosylation of AFP produced in fetal liver increased in inverse proportion to the gestation period, in weeks, indicating that fucosylation of AFP in HCC may be related to the dedifferentiation of human hepatocytes through malignant transformation.

Increase of fucosylated serum cholinesterase in relation to high risk groups for hepatocellular carcinomas.

Serum cholinesterase (ChE) (E.C. 3.1.1.8) is a glycoprotein which has 36 potential sites of asparagine-N-linked sugar chains. The structures of oligosaccharides released from ChE on hydrazinolysis were studied by serial lectin affinity column chromatography, exoglycosidase digestion, and methylation analysis. Seventy-three % of the sugar chains occurred as biantennary oligosaccharides and the remainder as C-2 and C-2,4/C-2,6 branched tri- and tetraantennary oligosaccharides. Several percentages of the Lewis X antigenic determinant and fucosylated mannose core were linked to them, and their sialic acid residues were linked to nonreducing terminal galactose residues at the C-3 and C-6 positions. Aleuria aurantia lectin-reactive ChE with the Lewis X antigenic determinant increased in hepatocellular carcinomas and liver cirrhosis compared with chronic hepatitis; on the other hand, Aleuria aurantia lectin-reactive ChE did not change significantly after transcatheter arterial embolization and was not related to the serum levels of alpha-fetoprotein and carcinoembryonic antigen in patients with hepatocellular carcinomas. Accordingly, the analysis of Aleuria aurantia lectin-reactive ChE is clinically useful for differentiating liver cirrhosis from chronic hepatitis and to identify high risk groups for hepatocellular carcinomas, i.e., cirrhotic patients in Child's A grade.

Intracellular lectins associated with N-linked glycoprotein traffic.

The vectorial intracellular transport of N-glycan-linked glycoproteins is indispensable for biological functions. In order to sort these glycoproteins to the correct destination, animal intracellular lectins play important roles as sorting receptors. The roles of such lectins in the biosynthetic pathway from the endoplasmic reticulum (ER) to the cell surface are addressed in this review. Calnexin and calreticulin function via specific carbohydrates in quality control of newly synthesized glycoproteins in the ER, and ERGIC-53 seems to function in the transport of glycoproteins from ER to the Golgi complex. In addition to the well-understood role of mannose 6-phosphate receptor in lysosomal protein sorting, the vesicular integral protein of 36 kDa (VIP36) functions as a sorting receptor by recognizing high-mannose type glycans containing alpha1-->2Man residues for transport from Golgi to the cell surface in polarized epithelial cells.

Determination of carbohydrate-deficient transferrin separated by lectin affinity chromatography for detecting chronic alcohol abuse.

Carbohydrate-deficient transferrin (CDT) has been established as a valuable biological marker for detecting chronic alcohol abuse. To improve the diagnostic efficiency, we studied new CDT determination procedures involving the use of lectin affinity chromatography with Allomyrina dichotoma agglutinin (allo A) and Trichosanthes japonica agglutinin I (TJA-I) to isolate the CDT isoforms CDT-allo A and CDT-TJA, respectively. These procedures, based on detection of the CDT-allo A and CDT-TJA isoforms in sera, showed high sensitivity (100% and 98%, respectively) and high specificity (93% and 85%, respectively). These results demonstrate that the new procedures involving the use of lectin affinity chromatography are more useful for isolating markers in the CDT test than the conventional charge-based separation method.

The receptor occupation and plasma concentration of NKY-722, a water-soluble dihydropyridine-type calcium antagonist, in spontaneously hypertensive rats.

1. The occupation in vivo by NKY-722 of 1,4-dihydropyridine (DHP) calcium antagonist receptors in myocardium, aorta and cerebral cortex was investigated. At 1 and 3 h after oral administration of NKY-722 (3 mg kg-1) in spontaneously hypertensive rats (SHR), there was a significant (44 and 41%, respectively) decrease in the number of myocardial (+)-[3H]-PN 200-110 binding sites (Bmax) compared to control values. A greater reduction of Bmax values was observed at 1 (86%), 3 (88%), 6 (63%) and 12 (46%) h later by a higher dose (10 mg kg-1) of this drug. The occupation of myocardial 1,4-DHP calcium antagonist receptors after oral administration of NKY-722 correlated significantly with its plasma concentration. There was a significant decrease in cerebral cortical (+)-[3H]-PN 200-110 binding (Bmax) at 1 and 3 h after oral administration of NKY-722 (10 mg kg-1). 2. Oral administration of nicardipine (10 mg kg-1) in SHR caused a significant reduction of Bmax values for (+)-[3H]-PN 200-110 binding in myocardium at 1 and 3 h later and in cerebral cortex at 1 h later. 3. The in vivo specific binding of (+)-[3H]-PN 200-110 in particulate fractions of aorta of SHR was significantly (79 and 83%, respectively) reduced at 1 and 6 h after oral administration of NKY-722 (3 mg kg-1), while myocardial (+)-[3H]-PN 200-110 binding was decreased by 52% only at 1 h later. Also, nicardipine administration reduced in vivo ( + )-[3H]-PN 200-110 binding in aorta at 1 and 6 h later and in myocardium at 1 h later. On the other hand, the administration of both NKY-722 and nicardipine had no significant effect on in vivo (+ )-[3H]-PN 200-110 binding in cerebreal cortex.4 It is concluded that NKY-722 may exert more selective and sustained occupation in vivo of 1,4-DHP calcium antagonist receptors in vascular tissues of SHR than in myocardial and brain tissues.

Obvious mRNA and protein expression but absence of mutations of the RET proto-oncogene in parathyroid tumors.

The study on the expression of the RET proto-oncogene in parathyroid tumors disclosed obvious mRNA expression by the reverse transcription (RT)-polymerase chain reaction (PCR) method and protein expression by Western blotting. To find out whether mutations in the cysteine-rich regions or tyrosine kinase domain of the RET proto-oncogene are etiological for parathyroid tumorigenesis, sporadic parathyroid adenomas and carcinomas, parathyroid tumors from multiple endocrine neoplasia 1, familial isolated hyperparathyroidism or hereditary hyperparathyroidism-jaw tumor syndrome were screened by PCR-single strand conformation polymorphism and PCR restriction fragment length polymorphism. Missense mutations in the cysteine-rich region, or codons 768 or 918 in the tyrosine kinase domain of the RET proto-oncogene, were not detected in any of the examined cases of parathyroid tumors. These results suggest that mutations of the RET proto-oncogene do not represent a frequent mechanism of tumorigenesis for parathyroid tumors.

Synthesis of lipid-linked oligosaccharides is dependent on the cell cycle in rat 3Y1 cells.

Synchronized cultures of rat 3Y1 cells, prepared by the density-arrested method, were used to investigate the relationship of N-glycosylation to the cell cycle. Although total cellular proteins were synthesized independently of the cell cycle, the synthesis of membrane-bound proteins was found to be dependent on the cell cycle, the time of maximum synthesis being just before that of maximum DNA synthesis. The synthesis of lipid-linked oligosaccharides (LLO), which are utilized as intermediates in N-glycosylation, increased in the S phase to a level at least ten times higher than in the G1, G2, and M periods. Moreover, the activities of dehydrodolichyl diphosphate synthase and farnesyl diphosphate synthase, which synthesize the precursors of dolichol, also increased in the S phase concomitantly with LLO synthesis. However, since the cell cycle dependency curves of these two enzyme activities were somewhat broader than that of LLO synthesis, the rate-limiting enzyme in the regulation of LLO synthesis might be another one such as dehydrodolichol reductase. These results suggest that LLO synthesis is regulated by multiple synthetic enzymes which are activated in a cell cycle dependent manner.

Electrospray ionization-mass spectrometric analysis of serum transferrin isoforms in patients with carbohydrate-deficient glycoprotein syndrome.

We previously reported that the carbohydrate-deficient glycoprotein (CDG) syndrome is an asparagine-N-linked sugar chain transfer deficiency [Yamashita et al. (1993) J. Biol. Chem. 268, 5783-5789]. In order to confirm this hypothesis, we applied electrospray ionization-mass spectrometric analysis to transferrin isoforms purified from patients with the CDG syndrome. Transferrin isoforms containing 4, 2, and 0 sialic acid residues, S4, S2, and S0, were separated by Mono Q anion exchange column chromatography from serum of a patient with the CDG syndrome. The molecular masses of S4, S2, and S0 were determined to be 79,570 +/- 5, 77,364 +/- 6, and 75,157 +/- 6 Da by electrospray ionization mass spectrometry (ESI/MS). The differences between S4 and S2, and between S2 and S0 were both in accordance with the molecular mass of a disialylated biantennary sugar chain [Neu5Ac alpha 2-->6Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->6(Neu5Ac alpha 2-->6Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->3)Man beta 1-->4GlcNAc beta 1-->4GlcNAc] (2,206 Da), showing that S0 is nonglycosylated, and that S4 and S2 carry 2 and 1 mol of asparagine-N-linked sugar chains, respectively. The nonglycosylated asparagine site of S2 was elucidated to be random by high performance liquid chromatography-ESI/MS of a tryptic peptide of reduced and pyridylethylated S2.ESI/MS analysis of transferrin purified through one step from serum is applicable for a definite diagnosis of the CDG syndrome.

Effect of exogenous dopamine on hypothalamic dopamine and norepinephrine concentrations in the neonatal brain in rats.

Hypothalamic dopamine (DA) and norepinephrine (NE) concentrations were studied in the neonatal rats after acute (postnatal day 4) or chronic (postnatal days 1-10) DA injections (0.5 mg in 5% dextrose in 0.45% saline). Acute injection of DA twice on postnatal day 4 resulted in an increase of hypothalamic DA and NE concentrations 16 hr later. Chronic treatment with the DA (twice in a day) for 10 days resulted in a reduction of NE concentration in the hypothalamus. The results of these studies suggest that the amount and duration of exposure to exogenous DA during postnatal development may result in divergent effects on hypothalamic catecholamine concentration.

Receptor occupation and pharmacokinetics of MPC-1304, a new Ca2+ channel antagonist, in spontaneously hypertensive rats.

MPC-1304, (+/-)-methyl 2-oxopropyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarbonate , is a novel 1,4-dihydropyridine Ca2+ channel antagonist with potent and long-lasting antihypertensive effects. We characterized the ex vivo and in vivo binding properties of MPC-1304 to Ca2+ channel antagonist receptors in myocardial, aortic and brain tissues of spontaneously hypertensive rats (SHR) by radioreceptor assay using [3H](+)-PN 200-110 ([5-methyl-3H](+)-PN 200-110 (4-(2,1,3-benzoxadiazol-4-yl)-1,4,-dihydro-5-methoxycarbonyl-2,6-d imethyl-1,4-dihydro-3-isopropylcarbonylpyridine-5-carboxylic acid methyl ester)). At 1 and 6 h after oral administration of MPC-1304 (10 mg/kg) in SHR, there was significant decrease (48%) in the number of [3H](+)-PN 200-110 binding sites (Bmax) in myocardial membranes compared to control values. The plasma concentration of MPC-1304 in SHR correlated significantly with the occupation by this drug of myocardial Ca2+ channel antagonist receptors. The in vivo specific binding of [3H](+)-PN 200-110 in particulate fractions of aorta of SHR was significantly reduced (74.8 and 37.9%, respectively) at 1 and 6 after oral administration of MPC-1304 (3 mg/kg), while the myocardial [3H](+)-PN 200-110 binding was decreased only at 1 h later. In these rats, there was little change in cerebral cortical [3H](+)-PN 200-110 binding. In conclusion, MPC-1304 exerted more selective and sustained occupation in vivo of Ca2+ channel antagonist receptors in vascular tissues of SHR than in those of myocardial and brain tissues.

Effect of postovulatory treatment with a luteinizing hormone-releasing hormone analog on the plasma level of progesterone in women.

(des-Gly-NH2(10),Pro-ethylamide9) luteinizing hormone-releasing hormone (LH-RH) (100 microgram) was administered subcutaneously once daily for 5 days during the postovulatory period in six women with regular menstrual cycles. Plasma levels of luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone were measured daily by radioimmunoassay from the ovulatory stage to menses. Suppression of plasma progesterone occurred during the treated luteal phase as compared with that of the control luteal phase. This finding suggests that repetitive, massive, endogenous luteinizing hormone or massive, exogenous, LH-RH itself during the early luteal phase of the cycle may induce functional luteolysis.

Detection of human immunodeficiency virus, hepatitis B virus, and hepatitis C virus in donor eyes using polymerase chain reaction.

Detection of human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) in donor eyes was performed. DNAs were extracted from the uvea, and they were amplified using the polymerase chain reaction (PCR). Amplified viral DNAs were detected with liquid hybridisation and chemiluminescent assay in which no radioactive materials were used. This method was shown to have a sensitivity limit of fewer than 10 copies of HIV, making it much more sensitive than the current techniques employed in eye banks. The method was applied to 120 donor eyes, including four from donors seropositive for HBV. The HBV gene was detected in one case in which the donor's blood had not been tested for HBV. HIV and HCV genes were not detected in any of the samples. The assay could be an effective screening test for the detection of these viruses in eye bank eyes.

In vivo receptor binding of novel alpha1-adrenoceptor antagonists for treatment of benign prostatic hyperplasia.

New types of alpha1-adrenoceptor antagonists (tamsulosin, KMD-3213 and JTH-601) are currently receiving a great deal of attention, especially in terms of developing effective therapeutic agents to treat bladder outlet obstruction with less side effects, such as postural hypotension, in patients with benign prostatic hyperplasia (BPH). In vivo alpha1-adrenoceptor binding properties of these antagonists in prostate and other tissues of rats were examined. Intravenous injections of tamsulosin, KMD-3213 and JTH-601 inhibited dose-dependently in vivo specific [3H]tamsulosin binding in various tissues. Ratios of ID50(aorta) to ID50(prostate) of KMD-3213 and JTH-601 were greater than those of tamsulosin and prazosin. Further, the ratios of ID50(spleen) to ID50(submaxillary gland) of these drugs were greater than that of prazosin. Following intravenous injections of [3H]KMD-3213 in rats, the amount of specific binding in prostate was significantly greater than that of [3H]prazosin, but that in aorta or spleen was much smaller. Interestingly, [3H]JTH-601 showed little in vivo specific binding in aorta. These data suggest that KMD-3213 and JTH-601 exhibit higher affinity to alpha1-adrenoceptors in prostate and submaxillary gland than in vascular tissues in vivo.

A sustained increase in beta-adrenoceptors during long-term therapy with metoprolol and bisoprolol in patients with heart failure from idiopathic dilated cardiomyopathy.

Effects of long-term therapy with beta 1-selective antagonists (metoprolol, bisoprolol) on beta-adrenoceptors in lymphocytes of patients with idiopathic dilated cardiomyopathy (DCM) were examined. There was a significant reduction in the number of lymphocyte beta-adrenoceptors in patients with DCM compared to that in healthy volunteers, as demonstrated by a selective decrease in maximum number of binding sites (Bmax) for (-)-[125I]iodocyanopindolol (CYP). A therapy with metoprolol and bisoprolol in these patients caused a marked increase in lymphocyte beta-adrenoceptor density. The significant increase was observed from 2 or 3 months after the start of therapy with these drugs, and it was maintained during the therapy for 24 months. The left ventricular ejection fraction in patients with DCM was improved by the long-term therapy with metoprolol and bisoprolol, and this effect seems to be correlated with an observed enhancement of lymphocyte beta-adrenoceptors in the time course. Also, the increase in lymphocyte beta-adrenoceptors appears to be correlated with a gradual amelioration in circulating catecholamine levels by the long-term therapy with beta-adrenoceptor antagonists in patients with DCM. Thus, the present study suggests that beta-adrenoceptors in lymphocytes of patients with DCM are up-regulated by a long-term therapy with metoprolol and bisoprolol.

Ex vivo occupancy by tamsulosin of alpha1-adrenoceptors in rat tissues in relation to the plasma concentration.

At 0.5-12 h after oral administration of tamsulosin (2.3 micromol/kg) in rats, there was a significant decrease in specific [3H]prazosin binding in the prostate as compared to the control value. The greater decrease occurred in the submaxillary gland. The effect of tamsulosin was mainly due to a marked reduction of [3H]prazosin binding sites (Bmax) rather than to an increase in the dissociation constant (Kd). In contrast, there was only a slight decrease or no change in the [3H]prazosin binding in the spleen, heart, and cerebral cortex of tamsulosin-administered rats at 0.5-12 h. Oral administration of terazosin (21.7 micromol/kg) significantly increased Kd values for [3H]prazosin binding with little effect on Bmax values in the rat prostate at 3 and 6 h. The greater increases in Kd values were observed in the submaxillary gland, spleen and heart at 0.5-12 h. Terazosin had a slight effect on Kd values for the cerebral cortical [3H]prazosin binding. Tamsulosin was absorbed rapidly after oral administration at a dose of 2.3 micromol/kg in rats, and at 6 h, plasma concentration decreased markedly to approximately one-twentieth of the 0.5 h peak level. alpha1-Adrenoceptor occupancy was estimated as a percentage of decrease in Bmax values for [3H]prazosin binding in tissues of tamsulosin-treated rats compared with control rats. The alpha1-adrenoceptor occupancy by tamsulosin in the prostate and submaxillary gland occurred rapidly in parallel with the rise in plasma concentration of tamsulosin, and lasted for over 12 h despite the marked decrease in plasma concentration. Consequently, it is suggested that tamsulosin produces more selective and sustained occupancy in vivo of alpha1-adrenoceptors in the submaxillary gland and prostate of rats than in other tissues.

Increased excretion of N-acetyl-beta-D-glucosaminidase and beta2-microglobulin in gestational week 30.

BACKGROUND: Little is known about when the urinary excretion of a combination of N-acetyl-beta-D-glucosaminidase (NAG) and beta2-microglobulin (beta2MG) concentration [relative to creatinine (Cr)] reaches maximal values during uncomplicated normotensive pregnancy. This study was thus designed to analyze when urinary excretion of biochemical parameters was increased during normotensive pregnancy. METHODS: NAG, beta2MG, total protein, albumin, and Cr were simultaneously measured in random (untimed) midstream urine samples from 22 healthy nonpregnant women and from 82 normotensive pregnant women (22 in gestational week 20, 25 in week 30, and 35 in week 37). RESULTS: NAG/Cr and beta2MG/Cr ratios were significantly higher (P < 0.01-0.05) in the normotensive pregnant women in gestational week 30 than in the nonpregnant control subjects and normotensive pregnant women in gestational week 20. The NAG/Cr and beta2MG/Cr ratios showed maximal values in gestational week 30. The total protein/Cr ratio was significantly higher in gestational weeks 20, 30, and 37 than in the control subjects. The albumin/Cr ratio was significantly higher in women in gestational week 30 and 37 than in women in gestational week 20 and in the control subjects. CONCLUSIONS: The excretion of both NAG and beta2MG relative to Cr was increased and showed the maximal values in gestational week 30 during normotensive pregnancy. The increase in a tubular enzyme (NAG) might be caused by renal tubular damage, and that in a low molecular weight protein (beta2MG) might result from decreased renal tubular reabsorption. These findings suggest that renal tubular damage and reabsorption dysfunction were increased in gestational week 30.

Determination of alpha 1-adrenoceptor antagonists in plasma by radioreceptor assay.

A simple, rapid and sensitive radioreceptor assay (RRA) for the quantification of alpha 1-adrenoceptor antagonists such as prazosin in plasma is described. The method involves the use of an RRA based on [3H]prazosin displacement in rat cerebral cortical membranes. The method is reliable, with intra-assay and inter-assay RSDs ranging from 5.9 to 9.2%. The limit of detection is 0.2 (prazosin hydrochloride), 0.05 (tamsulosin hydrochloride) and 0.3 (bunazosin hydrochloride) pmol per assay. Using this method the plasma levels of prazosin hydrochloride were determined in beagle dogs administered orally 2.39 mumol kg-1 of this drug. The plasma levels of prazosin in beagle dogs are in good agreement with those obtained using a high-performance liquid chromatography (HPLC). This RRA proved to be applicable to the monitoring of plasma prazosin levels in patients with essential hypertension and/or benign prostatic hypertrophy receiving therapy with this drug with the therapeutic dosage schedule. Thus, the concentrations of alpha 1-adrenoceptor antagonists in plasma can be adequately monitored by RRA as well as by HPLC.

Mature adrenomedullin concentrations in plasma during pregnancy.

OBJECTIVE: Adrenomedullin is a novel peptide that exerts a potent, dose-dependent and long-lasting hypotensive effect. In human plasma, adrenomedullin consists of two molecular forms: mature and immature. Immature adrenomedullin is much less bioactive than mature adrenomedullin. Although a gradual increase in plasma adrenomedullin has been reportedly observed as pregnancy progressed, mature adrenomedullin has not been examined. The aim of this study was to elucidate the plasma level of mature adrenomedullin in pregnant women. METHODS: We measured the concentrations of mature adrenomedullin in ten pregnant women in the first trimester, ten pregnant women in the third trimester, and ten non-pregnant controls with the immunoradiometric assay. RESULTS: The mean concentration of mature adrenomedullin was significantly increased in pregnant women in the first trimester compared to age-matched non-pregnant subjects (p < 0.05). The mean concentration of mature adrenomedullin was significantly increased in pregnant women in the third trimester compared with pregnant women in the first trimester (p < 0.005). CONCLUSION: Our study demonstrated that concentrations of mature adrenomedullin were elevated in pregnant women compared with non-pregnant women and its concentration in the third trimester was significantly higher than that in the first trimester.