The effect of methyl lidocaine on lysophospholipid metabolism in hamster heart

An important feature in the remodelling of fatty acyl chains in cellular phospholipids is the acylation of lysophospholipids. Since lysophospholipids are cytolytic at high concentrations, the acylation reaction may provide an alternate pathway for the removal of cellular lysophospholipids. However, the physiological role of the acylation process in the maintenance of lysophospholipid levels in mammalian tissues has not been clearly defined. In this study, methyl lidocaine was found to inhibit both lysophosphatidylcholine:acyl-CoA and lysophosphatidylethanolamine:acyl-CoA acyltransferase activities in the hamster heart, but the drug had no effect on the other lysophospholipid metabolic enzymes. When the heart was perfused with 0.5 mg methyl lidocaine/mL, acyltransferase activities were attenuated, but there was no change in the activities of phospholipase A or lysophospholipase. The levels of the major lysophospholipids in the heart were not altered by methyl lidocaine perfusion. When the hearts were perfused with labelled lysophospholipid in the presence of methyl lidocaine, there was a reduction in the formation of the phospholipid and an increase in the release of the free fatty acid. However, the labelling of lysophospholipid in the heart was not altered by methyl lidocaine. We postulate that the acylation reaction has no direct contribution to the maintenance of the lysophospholipid levels in the heart.     

Establishment and characterization of a human chorionic gonadotropin (hCG) producing cell line (RTSG) from an ovarian epithelial cancer

A new cell line designated RTSG established in vitro from the pleural effusion of a patient with metastatic ovarian epithelial cancer has been subcultured 46 times for more than 2 years. The cells grew in a monolayered sheet, showing a tendency to pile up, with the population doubling in 48 hrs. Electron-microscopically, desmosomes were characteristically observed, suggesting the cells were of epithelial origin. Chromosomal analysis revealed aneuploidy with a tetraploid mode. The heterotransplanted tumors in nude mice were histopathologically classified as a poorly differentiated adenocarcinoma, whereas the original tumor consisted mainly of mucinous and serous cystadenocarcinoma and only partly of poorly differentiated adenocarcinoma. The cells secreted hCG (38.8 mIU/day/10(6) cells) and beta-hCG (6.1 ng/day/10(6) cells) in spent medium. Immunocytologic +-and-histochemical staining for tumor markers of the original tumor, the cultured cells and the transplanted tumors also revealed the localization of not only hCG and beta-hCG but also CA19-9 and CA-125 whose values had been elevated in the preoperative serum (hCG: 10 mIU/ml, CA19-9: 6,400 U/ml, CA-125: 225 U/ml). Results of PAS, Alcian-blue and Mucicarmine strains indicated that most of the PAS-positive substances in the cultured cells and the transplanted tumors were consistent with glycogen while the original tumor mainly contained mucin except for the lesion of poorly differentiated adenocarcinoma with glycogen. These results suggested that the cultured cells might originate from poorly differentiated adenocarcinoma cells in the original tumor.     

Regulation of gene expression in rat prostate by androgen and beta-adrenergic receptor pathways

Denervation of rat ventral prostate has been accomplished by excising prostatic tissue fragments and implanting them under the renal capsules of intact syngeneic rats. This resulted in a substantial reduction of expression of a major organ-specific secretory protein, prostatic binding protein (PBP). The depressed level of PBP and its subunits and mRNAs could be restored, however, to as much as 80% of control levels by the administration of a pharmacological dose of exogenous androgen, testosterone propionate (TP), and/or a beta-adrenergic agonist, isoproterenol (ISO). Furthermore, compared to ascorbate-treated controls, TP and ISO increased the synthesis of total cellular protein and PBP by the prostatic renal implants. TP and/or ISO also remodelled the luminal epithelial structure and elevated secretory functions. ISO alone had no effect, however, in castrated animals, indicating that androgen plays a dominant role in the restoration of tissue PBP content. Concomitant to increased PBP content and remodelling of prostatic histomorphology, androgen was also found to raise the depressed levels of beta 2-adrenergic and androgen receptors in the prostatic isografts maintained in intact hosts. In contrast, although an established rat prostatic epithelial cell line (NbE-1) contains high affinity androgen receptor, androgen failed to restore beta-adrenergic receptor as well as PBP content in this cultured cell line. These results, taken together, suggest that a tight coupling between androgen receptor and beta 2-adrenergic receptor pathways may be a prerequisite for PBP expression and functional differentiation in the rat ventral prostate gland.     

Prolonged blood pressure reduction by orally active renin inhibitor RO 42-5892 in essential hypertension.

OBJECTIVE--To investigate the effects of a novel specific renin inhibitor, RO 42-5892, with high affinity for human renin (Ki = 0.5 x 10(-9) mol/l), on plasma renin activity and angiotensin II concentration and on 24 hour ambulatory blood pressure in essential hypertension. DESIGN--Exploratory study in which active treatment was preceded by placebo. SETTING--Inpatient unit of teaching hospital. PATIENTS--Nine men with uncomplicated essential hypertension who had a normal sodium intake. INTERVENTIONS--Two single intravenous doses of RO 42-5892 (100 and 1,000 micrograms/kg in 10 minutes) given to six patients and one single oral dose (600 mg) given to the three others as well as to three of the patients who also received the two intravenous doses. RESULTS--With both intravenous and oral doses renin activity fell in 10 minutes to undetectably low values, while angiotensin II concentration fell overall by 80-90% with intravenous dosing and by 30-40% after the oral dose. Angiotensin II concentration was back to baseline four hours after the low and six hours after the high intravenous dose and remained low for at least eight hours after the oral dose. Blood pressure fell rapidly both after low and high intravenous doses and after the oral dose and remained low for hours. With the high intravenous dose the daytime (0900-2230), night time (2300-0600), and next morning (0630-0830) systolic blood pressures were significantly (p less than 0.05) lowered by 12.5 (95% confidence interval 5.6 to 19.7), 12.2 (5.4 to 19.3), and 10.7 (3.2 to 18.5) mm Hg respectively, and daytime diastolic pressure was lowered by 9.3 (2.2 to 16.8) mmHg. With the oral dose daytime, night time, and next morning systolic blood pressures were lowered by 10.3 (5.5 to 15.4), 10.5 (4.2 to 17.2), and 9.7 (4.0 to 15.6) mm Hg, and daytime and night time diastolic pressures were lowered by 5.8 (0.9 to 11.0) and 6.0 (0.3-12) mm Hg respectively. CONCLUSIONS--The effect of the inhibitor on blood pressure was maintained over a longer period than its effect on angiotensin II. RO 42-5892 is orally active and has a prolonged antihypertensive effect in patients who did not have sodium depletion. This prolonged effect seems to be independent, at least in part, of the suppression of circulating angiotensin II.     

Repression of Asolectin-Dependent Activation of Partially Lipid Depleted ATPase Prepared from the Plasma Membrane-Enriched Fraction of Cucumber Roots due to Ca2+ Starvation

The ATPase activity of the plasma membrane-enriched fractionwas severely inhibited by withdrawal of Ca²⁺ from the mediumfor 5 days, although the root system appeared to be unaffectedto visual inspection. Partially lipid-depleted ATPases withsimilar ratios of phospholipid to protein were prepared fromthe plasma membrane-enriched fraction of cucumber roots culturedwith control medium and one lacking Ca²⁺, and their propertieswere compared. SDS disc polyacrylamide gel electrophoresis showedthat the polypeptide components were essentially similar betweencontrol and Ca²⁺-starved roots. Partially lipid-depleted ATPasereassociated with asolectin, the lecithin from soybean, showedtypical characteristics of plasma membrane type ATPase; pH optimumat 6.5, high specificity for ATP as substrate and strong inhibitionby vanadate but not nitrate. The activity of reassociated ATPaseobtained from the control roots was apparently higher than theactivity obtained from Ca²⁺-starved roots. The amount of asolectinrequired for maximum activation of the partially lipid-depletedATPase prepared from control roots was much lower than thatprepared from Ca²⁺-starved roots. Reassociation of partiallylipid-depleted ATPase with asolectin produced higher ATPaseactivity than that with individual phospholipids. The activationof partially lipid-depleted ATPase prepared from control rootswith asolectin was not inhibited by addition of a sample preparedfrom Ca²⁺-starved roots. Thus, a decrease in the functionalassociation of ATPase with phospholipids might be one of thephysiological injuries in root cell membranes of cucumber causedby Ca²⁺ starvation. ¹Permanent address: Department of Horticulture, College of Agriculture,Chonnam National University, Chonnam 500, Korea. (Received February 23, 1988; Accepted August 18, 1988)     

Increase in Proton-Transport Activity of Tonoplast Vesicles as an Adaptive Response of Barley Roots to NaCl Stress

H⁺-Transport activity of the vesicles prepared from barley rootswas studied at the early phase after application of NaCl stress.The activity reached maximal level at 3 days after the treatmentwith 200 mM NaCl which moderately reduced the growth. This activityincrease could be suppressed in the presence of cycloheximideand actinomycin D. The properties of the membrane vesicles associated with H⁺-transportactivity prepared from both control and NaCl-stressed rootssuggested that it was of tonoplast origin based on the followingfindings: optimal pH at 7.5, strong inhibition by nitrate butnot by vanadate, and stimulation by chloride. The density gradient centrifugation of vesicles with DextranT70 did not show any detectable difference in the distributionpatterns of H⁺-transport activities between control and NaClstressedroots. Furthermore, K_m values for ATP of the H⁺-transport activityof vesicles prepared from control and NaCl-stressed roots werethe same. Therefore, H⁺-transport activity with properties similarto those of the control roots was increased by NaCl stress.The results are discussed in terms of an adaptive mechanismof barley against salt stress. ¹Permanent address: Department of Horticulture, College of Agriculture,Chonnam National University, Chonnam 500, Korea. (Received April 18, 1988; Accepted July 20, 1988)     

l-Glutamate-Dependent Medium Alkalinization by Asparagus Mesophyll Cells : Cotransport or Metabolism?

Mechanically isolated Asparagus sprengeri Regel mesophyll cells cause alkalinization of the suspension medium on the addition of l-glutamate or its analog l-methionine-d,l-sulfoximine. Using a radiolabeled pH probe, it was found that both compounds caused internal acidification whereas l-aspartate did not. Fusicoccin stimulated H⁺ efflux from the cells by 111% and the uptake of l-[U-¹⁴C]glutamate by 55%. Manometric experiments demonstrated that, unlike l-methionine-d,l-sulfoximine, l-glutamate stimulated CO₂ evolution from nonilluminated cells. Simultaneous measurements of medium alkalinization and ¹⁴CO₂ evolution upon the addition of labeled l-glutamate showed that alkalinization was immediate and reached a maximum value after 45 minutes whereas ¹⁴CO₂ evolution exhibited a lag before its appearance and continued in a linear manner for at least 100 minutes. Rates of alkalinization and uptake of l-[U-¹⁴C]glutamate were higher in the light while rates of ¹⁴CO₂ evolution were higher in the dark. The major labeled product of glutamate decarboxylation, γ-aminobutyric acid, was found in the cells and the suspension medium. Its addition to the cell suspension did not result in medium alkalinization and evidence indicates that it is lost from the cell to the medium. The data suggest that the origin of medium alkalinization is co-transport not metabolism, and that the loss of labeled CO₂ and γ-aminobutyric acid from the cell result in an overestimation of the stoichiometry of the H⁺/l-glutamate uptake process.     

Spectral analysis of ventilation in elderly subjects awake and asleep

We studied the periodicities of ventilation in elderly subjects using digital comb filtering. Two groups of subjects were studied, those with and without sleep apnea. Measurements were made in wakefulness, stage 1-2 sleep, and where possible in stage 3-4 sleep. For each of the digital filters we calculated the average power of the oscillatory output. To compare subject groups we first specifically determined the average power in the filter with the maximum output. The mean of this measurement was greater in elderly subjects with apnea compared with those without apnea, both during wakefulness and stage 1-2 sleep. In both groups of subjects the cycle time of the major ventilatory oscillations was on the order of 40-60 s. There was no difference in this cycle time between the two groups of subjects in wakefulness or stage 1-2 sleep. Thus, whereas similar oscillatory processes occur in subjects with and without apnea, it is the magnitude of the oscillation that differs between the two groups. These conclusions are supported by analysis of the output of individual filters of the digital comb filter. In both groups, stage 1-2 sleep produced significantly increased oscillations in ventilation. Both in wakefulness and stage 1-2 sleep, significantly greater periodicities occurred in the apneic compared with the nonapneic group. In the few subjects who had sufficient data in stage 3-4 sleep for spectral analysis, ventilatory oscillations were virtually absent in this state. Our data suggest that subjects who develop apnea during sleep have an increased propensity for periodic breathing even while awake.