Downregulation of [3H]Ro5-4864 binding sites after exposure to peripheral-type benzodiazepines in vitro

Peripheral-type benzodiazepine (BZD) binding sites undergo a rapid and pronounced downregulation after exposure to these compounds in vitro. Friend erythroleukemia cells were incubated with micromolar concentrations of BZD after which they were washed thoroughly and the binding of the specific peripheral-type BZD radioligand [3H]Ro5-4864 was determined. Exposure to the peripheral-type BZD Ro7-3351 decreased the number of [3H]Ro5-4864 binding sites from 324 to 41 fmol/10(6) cells with no change in affinity. Downregulation appears to require active cellular processes because it is blocked when exposure to BZD is at 4 degrees C rather than at 37 degrees C. Furthermore, whereas [3H]Ro5-4864 binding is decreased substantially in membrane preparations made from downregulated cells, it is not altered when membrane preparations from control cells are exposed to BZD. The time course of downregulation is quite rapid, as it occurs within minutes. In contrast, the return of sites requires days and there is a close relationship between return of sites and growth of new cells. The ability of BZDs to downregulate correlates more closely with affinity for the peripheral-type site than with biological activity. The ability to undergo downregulation is characteristic of receptors and its occurrence suggests that peripheral-type BZD binding sites are functional receptors.

Sympathetic nervous system and blood pressure maintenance in the Brattleboro DI rat

Experiments were performed to determine the functional role of the sympathetic nervous system (SNS) in blood pressure regulation in Brattleboro diabetes insipidus (DI) rats and to determine the effects of synthetic arginine vasopressin (AVP) on sympathetic function in DI rats. The experiments were conducted in male age-matched Long-Evans (LE) and DI rats in the conscious unstressed state. Mean arterial pressure (MAP) and heart rate were similar in conscious unstressed LE and DI rats, but basal plasma concentrations of norepinephrine (NE) and epinephrine (E) were elevated in DI rats compared with LE rats. An intra-arterial bolus injection of hexamethonium (30 mg/kg) resulted in greater reductions of MAP in DI rats (-62 +/- 5 mmHg) than in LE rats (-42 +/- 7 mmHg; P less than 0.05). Administration of AVP to DI rats by osmotic minipump reduced plasma NE concentration in DI rats to a level not different from that in LE rats, but E concentration remained elevated. AVP administration to DI rats also reduced the hexamethonium-induced fall in MAP in these animals (-47 +/- 7 mmHg) to a level not different from that in LE rats. We conclude that the SNS plays a greater role in blood pressure maintenance in conscious DI rats than in LE rats and that AVP administration can normalize plasma NE concentration and the contribution of the SNS to blood pressure maintenance in these animals.

Stable gene amplification and overexpression of sodium- and potassium-activated ATPase in HeLa cells

Cell lines stably resistant to ouabain were isolated from an unstably resistant HeLa line after growth in nonselective medium. Stable resistant lines bound ouabain at levels 10-fold higher than did HeLa cells and at similar levels to those bound by the unstable C+ line previously described (J. F. Ash, R. M. Fineman, T. Kalka, M. Morgan, and B. Wire, J. Cell Biol. 99: 971-983). Expression and synthesis of the Na+, K+ -ATPase alpha chain showed a similar amplification over that for HeLa cells by Western blots and [35S]methionine pulse-labeling. In addition, a glycoprotein labeled with [3H]fucose and comigrating with the Na+, K+ -ATPase beta chain was eight- to ninefold amplified in stably resistant lines. Dot blots with a cDNA clone specific for Na+, K+ -ATPase alpha chain gene sequences confirmed the amplification of this gene. Karyotyping suggested that the amplification is associated with an expanded, abnormal banded region on the long (q) arm of one chromosome 17.

Role of central serotonin systems in the stimulatory effects of ovarian hormones and naloxone on luteinizing hormone release in female rats

The present experiments tested whether serotonergic neurons that innervate discrete areas of the hypothalamus are involved in the stimulation of LH release by ovarian hormones or the opiate antagonist naloxone in female rats. Ovariectomized rats received oil vehicle, estradiol benzoate (EB) alone, or EB followed by progesterone (P) 2 days later. Serotonin (5-HT) activity was assessed from the accumulation observed after the administration of the monoamine oxidase inhibitor pargyline. Two days after EB treatment, LH concentrations were reduced in the morning and rose by later afternoon. Administration of P to EB-primed rats stimulated a LH surge. This latter treatment also enhanced pargyline-induced 5-HT accumulation, suggesting increased 5-HT activity, in the medial preoptic nucleus and interstitial nucleus of the stria terminalis, but reduced 5-HT accumulation, suggesting decreased 5-HT activity, in the ventromedial nucleus. 5-HT activity was unaffected after EB alone, either in the morning or afternoon, or by the administration of naloxone to EB-primed rats. Specific depletion of 5-HT in the medial preoptic/stria terminalis area, achieved by microinjection of the neurotoxic indoleamine 5,7-dihydroxytryptamine resulted in a blockade of the LH surge induced by EB plus P. The present results suggest that central 5-HT neurons innervating the preoptic area are involved in the LH surge induced by progesterone, but not in the increases in LH occurring after treatment with estradiol alone or after blockade of opiate receptors.

Relative natriuretic activities of synthetic atriopeptins I, II and III

Recent evidence indicates that mammalian atria contain a series of peptides which possess potent natriuretic activity. Using a sensitive and reproducible bioassay developed by this laboratory, the natriuretic and diuretic activities of three peptides, atriopeptins I, II, and III (21, 23 and 24 amino acids, respectively) were compared. Bioassays were conducted in pentobarbital-anesthetized male Sprague-Dawley rats weighing 300-350 grams. At doses ranging from 0.33 to 3.0 micrograms, no significant differences in natriuretic or diuretic activities were observed between the three peptides. The time courses of the natriuretic and diuretic responses to these peptides were also identical. The finding that atriopeptin I (21 amino acids) possesses natriuretic activity equal to that of atriopeptins II and III suggests that the C-terminus residues of atriopeptin III (Phe-Arg-Tyr) are not necessary for full expression of natriuretic activity. However, since several previous reports have indicated that atriopeptin I is considerably less potent as a natriuretic than we report here, perhaps a cautionary note should be sounded concerning the conditions required to produce or to retain full biologic activities of the synthetic atriopeptins.

Alterations in amino acid transport in Na,K-ATPase amplified HeLa cells

Amino acid transport was studied in C1 cells which contain amplified levels of sodium- and potassium-activated adenosine triphosphatase (Na,K-ATPase), in C4 cells which are ouabain-sensitive revertants, and in parental HeLa S3. Sodium-dependent uptake of aminoisobutyric acid and alanine was increased 2-fold in the amplified C1 cells. After a 6 h amino acid starvation period, the rate of sodium-dependent uptake of methylaminoisobutyric acid was 70-90% greater for C1 than for C4 and HeLa. This uptake was inhibitable by ouabain and the apparent Km values for high affinity uptake were similar in all three lines. Overall, neutral amino acid uptake through Systems A, ASC, and L was 2-fold higher in the Na,K-ATPase amplified C1 cells relative to C4 or HeLa. The induction of System A uptake of methylaminoisobutyric acid after starvation was more rapid in both the amplified C1 cells and the revertant C4 when compared to HeLa, which suggests that the selection for amplification of the Na,K-ATPase produced membrane alterations affecting the adaptive regulation of System A.

Effects of histamine receptor antagonism on adrenaline-induced changes in blood pressure in intact dogs

This study was designed to test the hypothesis that histamine may contribute to the vasodepressor response which occurs in response to physiologic increments in adrenaline concentration in intact animals. Accordingly, following a control period of 30 min, adrenaline was infused intravenously for 45 min at a rate of 250 ng/kg per min in 14 anaesthetized dogs (Group I). A second group of eight dogs received an identical adrenaline infusion following complete H1- and H2-histamine receptor antagonism with tripelennamine plus cimetidine (Group II). A time control group of experiments, in which no drugs were infused, as well as groups receiving adrenaline plus either tripelennamine or cimetidine, were also performed. In Group I, adrenaline infusion increased heart rate and reduced mean arterial blood pressure by 10 mmHg (P less than 0.01). Following combined H1- and H2-histamine receptor antagonism (Group II), adrenaline infusion failed to reduce mean arterial blood pressure. However, mean arterial blood pressure was reduced significantly in the groups receiving adrenaline plus only one of the histamine receptor blocking agents. Since only the combined histamine receptor blockade completely eliminated the vasodepressor response to adrenaline, the data suggest that histamine may play a physiological role in the vasodepressor response to circulating adrenaline in the intact animal, and that both H1- and H2-histamine receptors may be involved.

A highly sensitive immunoassay system involving antibody-coated tubes and liposome-entrapped dye

In this colorimetric immunoassay for digoxin, large, unilamellar phospholipid vesicles approximately 0.2 micron in diameter are loaded with high concentrations of Sulforhodamine B. Digoxigenin coupled to phosphatidylethanolamine, incorporated into the lipid formulation, confers immunological specificity. The liposomes are then used as tracers in simple competitive-binding immunoassays with antibody-coated tubes. Results are amplified by 10(3) to 10(4) of what could be achieved with one label group attached to each hapten, so that the results can be read spectrophotometrically. The stability of the liposomes is excellent. The method should be applicable to measuring a wide variety of analytes.

A highly sensitive immunoassay system involving antibody-coated tubes and liposome-entrapped dye

In this colorimetric immunoassay for digoxin, large, unilamellar phospholipid vesicles approximately 0.2 micron in diameter are loaded with high concentrations of Sulforhodamine B. Digoxigenin coupled to phosphatidylethanolamine, incorporated into the lipid formulation, confers immunological specificity. The liposomes are then used as tracers in simple competitive-binding immunoassays with antibody-coated tubes. Results are amplified by 10(3) to 10(4) of what could be achieved with one label group attached to each hapten, so that the results can be read spectrophotometrically. The stability of the liposomes is excellent. The method should be applicable to measuring a wide variety of analytes.

Effect of intravenous epinephrine infusion on plasma renin activity in adrenalectomized dogs

Previous experiments have shown that circulating epinephrine stimulates renin secretin and increases plasma renin activity (PRA) when it is infused intravenously, but not when it is infused directly into the renal artery at similar infusion rates. The present experiments were designed to test the hypothesis that the adrenal glands mediate the PRA response to intravenous epinephrine infusion. Accordingly, anesthetized dogs were prepared with either an acute bilateral adrenalectomy or a sham-adrenalectomy procedure. Epinephrine was then infused intravenously into each animal for 45 minutes at a rate of 25 ng X kg-1 X min-1. Time control experiments in which epinephrine was not infused were also conducted. In sham-adrenalectomized dogs, PRA (in nanograms per ml h-1) rose from 4.1 +/- 1.4 in the control period to 13.0 +/- 3.0 during intravenous epinephrine infusion (means +/- SE; p less than 0.01). In adrenalectomized dogs, PRA rose from 2.1 +/- 0.4 during the control period to 5.5 +/- 0.9 during intravenous epinephrine infusion (p less than 0.01). Neither the absolute increments in PRA nor the percent increases in PRA were significantly different between the two groups receiving epinephrine. PRA remained unchanged in time control experiments. These data demonstrate that the adrenal glands need not be present in order for intravenous epinephrine infusion to elicit an increase in PRA. The data do not support the hypothesis, therefore, that epinephrine-induced increases in PRA are initiated by receptors located within the adrenal glands.

Quinolinic acid stimulates luteinizing hormone secretion in female rats: evidence for involvement of N-methyl-D-aspartate-preferring receptors

Pharmacological evidence suggests that endogenous excitatory amino acid neurotransmitters stimulate luteinizing hormone (LH) secretion in neonatal and adult rats. Recent studies have identified quinolinic acid (QUIN), an endogenous brain and peripheral metabolite of tryptophan, as a potent agonist at N-methyl-D-aspartate (NMDA)-preferring excitatory amino acid receptors. The present studies examined whether QUIN alters LH secretion in ovariectomized, estradiol-primed rats and whether such effects are mediated by specific amino acid receptor subtypes. In one experiment, animals received intracisternal injections of either quinolinic acid, N-methyl-DL-aspartate (NMA), aspartate (ASP), quisqualic acid (QA), or monosodium glutamate (GLU) five minutes prior to decapitation. In a second study, animals receiving central QUIN or NMA were treated simultaneously with either 2-amino-7-phosphonoheptanoic acid (APH) or kynurenic acid (KYA), both antagonists of NMDA-preferring receptors, or the quisqualate antagonist, glutamate diethyl ester (GDEE). Serum LH concentrations were measured by radioimmunoassay. Intracisternal administration of either QUIN or NMA resulted in an acute, dose-dependent increase of serum LH concentrations. Coadministration of APH blocked the effects of QUIN and NMA. QUIN stimulation of LH was also blocked by KYA, but not GDEE. Neither GLU nor ASP increased LH release, but QA did produce a small, significant elevation of LH. Light microscopic evaluation of brains showed no morphologic disturbance resulting from administration of these agents. The present results suggest that QUIN, or other endogenous ligands of NMDA-preferring receptors, may participate in the regulation of LH secretion in the adult female rat.

Quinolinic acid stimulates luteinizing hormone secretion through a serotonin-dependent mechanism

Previous results from this laboratory suggest that the tryptophan metabolite, quinolinic acid (QUIN), stimulates luteinizing hormone (LH) secretion in female rats, most likely through actions on NMDA-preferring excitatory amino acid receptors. The present experiments examined whether QUIN alters LH secretion through actions requiring intact catecholaminergic or serotonergic mechanisms. Each study examined the effects of intracisternal (i.c.) injections of 25 microliter acidic saline or saline containing QUIN (500 nmol) or the synthetic analogue, N-methyl-DL-aspartate (NMA, 500 nmol), into ovariectomized, estradiol benzoate-primed rats after pharmacologic disruption of monoaminergic neurotransmission. In each experiment, animals were decapitated 5 min after QUIN or NMA administration. Experiment 1 examined whether reduction in brain serotonin (5-HT) or of norepinephrine (NE) and epinephrine (E) alters the QUIN- or NMA-induced stimulation of LH secretion. Rats were pretreated with the dopamine-beta-hydroxylase inhibitor, FLA-63 (40 mg/kg 2 h prior). A second experiment examined the effects of the 5-HT antagonist, methysergide, on QUIN or NMA stimulation of LH secretion. Methysergide (15 mg/kg) was administered 30 min prior to experimentation. Experiment 3 examined whether selective destruction of raphe serotonergic neurons with the indoleamine neurotoxin, 5,7 dihydroxytryptamine (5,7 DHT), alters QUIN's stimulatory effects. In each study, serum LH concentrations were determined by radioimmunoassay. Hypothalamic catecholamine and 5-HT concentrations were measured by radioenzymatic assay and liquid chromatography with electrochemical detection, respectively. Depletion of brain 5-HT with PCPA significantly reduced the stimulation of LH secretion by QUIN, but not by NMA.(ABSTRACT TRUNCATED AT 250 WORDS)

Serial cultivation of normal rat bladder epithelial cells in vitro

Recent advances in culture techniques for human urothelial cells have led to the development of an improved method for growing primary rat bladder epithelial cells. We report here the conditions developed for large-scale in vitro growth and serial cultivation of normal diploid rat bladder epithelial cells. Primary cultures were initiated by attachment of bladder mucosal explants to type I collagen gels. A rapid outgrowth of epithelial cells from the explants occurred when cultured in a hormone-supplemented medium with epidermal growth factor. These primary outgrowths were passaged by nonenzymatic dispersion with 0.1 per cent ethylenediaminetetracetic acid and replating onto new gels. The capacity for routine serial passaging and maintenance of rat bladder epithelial cells required the presence of epidermal growth factor, a requirement not observed with human urothelial cells. The characteristics of the cultured rat bladder epithelial cells were similar to human urothelial cells in: ultrastructural and phase-contrast morphologic properties, showing junctional complexes, desmosomes, stratification and an apical glycocalyx; the absence of stromal cell contamination; and the ability to be serially passaged. Spontaneous cell-line formation was observed with the rat bladder epithelial cells, but has not been found with the human urothelial cells. With the method that we have developed, the number of rat bladder epithelial cells generated from a single bladder of a 4 to 6 week old rat was increased 100-fold from about 7 X 10(5) cells to 7 X 10(7) viable cells within 3 weeks of culture. The capability of culturing normal, primary rat bladder epithelial cells on this scale has not been reported previously and will facilitate comparative studies of the biological and molecular characteristics of the mammalian urothelium. Furthermore, this culture system will be useful for carcinogenesis studies, including metabolic activation of carcinogens and cellular transformation in vitro.

An improved bioassay method for determining natriuretic activity of atrial extracts

Extracts of mammalian atrial tissue contain potent natriuretic substances known collectively as atrial natriuretic factor (ANF). The purposes of the present experiments were: 1) to improve on existing bioassay methodology for the detection of ANF activity in atrial extracts, and 2) to compare the ANF activity of atrial extracts prepared from Brattleboro-stain diabetes insipidus (DI) rats with that from normal and water-deprived Long-Evans (LE) rats. A pool of atrial tissue extract (AE) was prepared from normal Sprague-Dawley rats for use as a standard against which unknown AE samples could be compared. Five doses, ranging from 27 to 432 micrograms of AE protein, were assayed in the Sprague-Dawley bioassay rats. Phosphate-buffered saline (PBS) vehicle and ventricular tissue extracts were also assayed. Statistical analysis of several log dose-response relationships revealed that the bioassay response most appropriate in determining relative natriuretic activity of AE was the log of the experimental/control ratio for sodium excretion. The bioassay was used to demonstrate that PBS atrial extracts from both water-deprived LE rats and DI rats contain more natriuretic activity than do PBS atrial extracts from LE rats.

Bioconversion and macromolecular binding of 2-amino-4-(5-nitro-2-furyl)thiazole by cultured rat urothelial cells

Bioconversion and binding of 2-amino-4-(5-nitro-2-furyl)-thiazole (ANFT) were examined using cultured rat bladder epithelial cells from weanling male F344 rats. Bladder cells were obtained in large quantities from outgrowths of dissected explants which were grown on collagen gels. Metabolic potential of rat urothelial cells to activate ANFT was evaluated by incubating primary culture cells with [2-14C]ANFT for 48 hr. Metabolites were subsequently analyzed by chromatographic and spectroscopic methods. Thin-layer chromatography of the ethyl acetate:diethyl ether (1:1, v/v) extract of the culture medium revealed two regions of radioactivity with Rf values of 0.12 and 0.60, the former corresponding to ANFT and the latter to one of its metabolites. High-pressure liquid chromatography of the solvent extract revealed two major peaks, with retention times of about 4 and 9 min, corresponding with the metabolite and ANFT, respectively. Low-resolution mass spectrum of the isolated metabolite showed a molecular ion at m/e 181. The metabolite was identified as 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone based on its chromatographic and spectral characteristics in comparison with the synthetic compound. About 24% of the recovered radioactivity from the culture medium was extractable into the organic phase, a majority of which was identified as 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone. Analysis of binding to proteins and nucleic acids prepared following exposure of [2-14C]ANFT revealed a 15- and 9-fold greater amount of binding, respectively, in cultures incubated with bladder cells than their corresponding heat-inactivated controls. Furthermore, homogenates of cultured bladder cells reduced ANFT on anaerobic incubation with reduced nicotinamide adenine dinucleotide phosphate to generate 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone. On reduction of [2-14C]ANFT with rat bladder or liver homogenates, about 23 and 11%, respectively, of the initial amounts of radioactivity were bound to the trichloracetic acid-insoluble fraction. These data demonstrate that rat bladder cells possess the metabolic capability to reduce ANFT and to generate reactive intermediate(s) that bind to cellular macromolecules.

Effects of the serotonin agonist, quipazine, on luteinizing hormone and prolactin release: evidence for serotonin-catecholamine interactions

The present study tested whether administration of the serotonin agonist, quipazine maleate, affects the secretion of luteinizing hormone (LH) and prolactin (PRL) and concomitantly, the activity of central noradrenergic and dopaminergic systems. Quipazine (15 mg/kg, ip) significantly reduced LH and increased PRL when administered to ovariectomized rats. Associated with these changes, the depletion of dopamine seen after synthesis inhibition with alpha-methyl tyrosine was reduced by quipazine in the caudate nucleus and median eminence, suggesting a depression of dopaminergic activity. The depletion of norepinephrine in the median eminence was unaffected. In a second experiment, quipazine (1 microM) diminished the potassium-induced release of both norepinephrine and dopamine from fragments of medial basal hypothalamus, in vitro. Release from preoptic area was unaffected. These results suggest that central serotonergic systems may interact with noradrenergic and dopaminergic systems that regulate LH and PRL secretion, respectively.

Risk of stomach cancer after gastric surgery for benign conditions. A case-control study

Patients with previous gastric surgery for benign conditions are thought to be at increased risk for gastric cancer based on studies from Europe. Recommendations have been made to screen these patients repeatedly in order to detect early gastric cancers. We conducted a case-control study to estimate the risk in the United States where the rates of gastric cancer are lower. There were 521 gastric cancer cases who were matched by age, race, sex, and date of admission to an equal number of hospital controls. The odds ratio for cancer after gastric surgery was 0.7 (P = 0.4) which indicates no increased risk. The sample size was sufficient to detect risks in the range reported in previous studies. The odds ratios rose with longer postoperative intervals but were based on small numbers and were not statistically significant. This case-control study failed to demonstrate an overall increased risk for gastric cancer after surgery. Further study is needed before general screening can be endorsed in the United States.

Effects of a beta 1-adrenoceptor agonist, prenalterol, on renal function and renin secretion rate in anesthetized dogs

Experiments were conducted to examine the effects of prenalterol on renal function and renin secretion in anesthetized dogs. Specifically, we tested whether prenalterol alters renal function directly, or only indirectly as a consequence of a systemic action of the drug. Accordingly, prenalterol was infused into one renal artery for five consecutive 15-min periods, at incremental rates of 0.1, 0.3, 0.9, 2.7, and 8.1 micrograms X kg-1 X min-1. Heart rate and mean arterial blood pressure were recorded, and renal functions and renin secretion rates were measured bilaterally. Direct intrarenal prenalterol infusion caused a 60 bpm increase in heart rate and resulted in marked increases in renin secretion rates from both kidneys. Intrarenal prenalterol infusion also reduced urinary sodium and potassium excretions bilaterally and equally. There were no consistent changes in mean arterial blood pressure, or in glomerular filtration rate or renal blood flow, during prenalterol infusion. We conclude that although prenalterol increases renin secretion rate markedly and may alter renal electrolyte excretion, these effects are not mediated by a direct intrarenal action of the drug.

Circulating epinephrine stimulates renin secretion in anesthetized dogs by activation of extrarenal adrenoceptors

The present experiments were designed to determine the location of the adrenoceptors responsible for initiating epinephrine-induced stimulation of renin secretion in vivo. Three hypotheses were tested: 1) the receptors are located intrarenally, 2) the receptors are located extrarenally , and 3) an interaction exists between intrarenal receptors and some event initiated by extrarenal receptors. All experiments were conducted in anesthetized dogs surgically prepared for renal clearance studies. Intravenous infusion of epinephrine at 250 ng X kg-1 X min-1 increased one-kidney renin secretion rate more than fivefold. In contrast, direct intrarenal infusion of epinephrine at 25 ng X kg-1 X min-1 only doubled renin secretion rate from the infused kidney. In six animals in which renin secretion rates were measured bilaterally during intrarenal epinephrine infusion, no differences in renin secretion rates were detected between the two kidneys. To examine the hypothesis that an interaction exists between intrarenal and extrarenal adrenoceptors, epinephrine was infused intravenously at 25 ng X kg-1 X min-1 and simultaneously into one renal artery at 10 ng X kg-1 X min-1. Renin secretion rates rose significantly (P less than 0.01) but equally from both kidneys. At lower epinephrine infusion rates (10 ng X kg-1 X min-1 intravenously plus 3 ng X kg-1 X min-1 intrarenally), renin secretion rates increased submaximally but still equally from both kidneys. It is concluded that epinephrine-induced stimulation of renin secretion in vivo is initiated by adrenoceptors located only extrarenally .

Effects of opiate antagonists on serotonin turnover and on luteinizing hormone and prolactin secretion in estrogen- or morphine-treated rats

Previous findings indicate that estradiol benzoate (EB) acutely activates serotonergic projections in the medial preoptic area that are stimulatory to prolactin (PRL) secretion. Because opioid agonists also stimulate both PRL release and serotonin (5-HT) turnover, the present experiments tested whether endogenous opioid neurons may mediate estrogen feedback effects. In experiment 1, ovariectomized rats received either 50 micrograms EB or oil vehicle, and either saline or a long-acting opiate receptor blocker, nalmetrene (10 mg/kg), simultaneously, 3 h prior to decapitation. The pargyline method was used to determine 5-HT turnover; hence members of each treatment group received either saline or pargyline (75 mg/kg i.p.) 30 min prior to decapitation. Plasma PRL and luteinizing hormone (LH) concentrations were determined by radioimmunoassays, and 5-HT concentrations from microdissected, individual brain nuclei were measured by liquid chromatography with electrochemical detection. Nalmetrene blocked both the acute elevation of PRL and the increase in 5-HT turnover in the medial preoptic nucleus and ventromedial nucleus induced by EB. Nalmetrene alone also enhanced LH release and 5-HT turnover in the bed nucleus of the stria terminalis, and these effects were prevented by EB. A second study tested whether the opioid agonist, morphine, mimics estrogen effects on PRL and preoptic 5-HT turnover. Animals received saline, morphine (10 mg/kg i.p.) and/or naloxone (5 mg/kg i.p.) 30 min prior to decapitation. Simultaneously, half in each group received pargyline as above.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-renin dependent hypertension in renal allograft rejections. A structural and functional analysis

A 25-year-old recipient of a cadaveric renal allograft underwent three acute rejection episodes within the first 40 days after transplant, the final episode necessitating nephrectomy. The saralasin acetate infusion test and plasma renin activity (as measured by radioimmunoassay of angiotensin I) were used as functional tests of the renin-angiotensin axis. Biopsy specimens of the allograft one hour after implantation and sections of the nephrectomy specimen were fixed and stained with hematoxylin-eosin for structural analysis. On three separate dates, during the final rejection episode, saralasin acetate infusion of up to 20 micrograms/kg/min failed to lower BP significantly. The final two trials were preceded by furosemide administration the previous day to reduce fluid volume. Plasma renin activity was low on all three dates. On nephrectomy, the allograft was noted grossly to be infarcted. Histologic examination revealed cortical necrosis, markedly narrowed or occluded intrarenal vessels, and extremely narrowed large vessels within the renal pelvis. The allograft renal artery was thickened and narrowed. From our structural and functional analysis we conclude that (1) hypertension, in this case, was probably volume dependent and was clearly renin independent; and (2) the low renin levels are explainable on the basis of extensive vascular occlusion producing renal infarction and resulting in a kidney incapable of producing significant amounts of renin (autonephrectomy).

Saralasin acetate test in renal transplant hypertension. Report of 17 cases and a review of the literature

The saralasin acetate test was performed in 17 hypertensive patients with renal transplants. These results were compared with 39 previously published reports of transplant patients who had been tested in the same manner. Eighty-two percent of our patients had a positive saralasin acetate test, suggesting renin-dependent hypertension. Baseline plasma renin activity (PRA) was significantly higher in patients with positive tests (6.96 +/- 1.75 v 2.88 +/- 0.53 ng/mL/hr). However, positive tests were obtained in several patients who had normoreninemia, and PRA levels did not correlate with the magnitude of vasodepressor BP response to saralasin. Transplant artery stenosis, acute rejection, and chronic rejection were the most common posttransplant complications associated with a positive test, but several patients had hypertension alone. While highly sensitive for renin-dependent hypertension posttransplantation, the test had poor specificity for identification of any one cause of posttransplant hypertension.

The importance of age on prostaglandin E2 excretion in normal and hypertensive men

Previous studies have shown reduced levels and total urinary excretion of prostaglandin E2 in a heterogeneous population of patients with hypertension. The following study was undertaken to extend these observations to focus on the influence of age and blood pressure on renal prostaglandin E2 excretion in males. Four groups of human subjects were studied on an ad libitum diet of at least 2 g salt per day: group 1 consisted of normal young men; group 2 consisted of young men with essential hypertension; group 3 consisted of older nonhypertensive men; group 4 consisted of older hypertensive men. Reduced urinary prostaglandin E2 excretion was seen in the elderly hypertensive group but not the young hypertensives. Thus, when all hypertensives were compared to control the reduced prostaglandin E2 excretion was accounted for primarily by the elderly hypertensives. The reduction of prostaglandin E2 excretion could not be accounted for by normal ageing alone. Whether cause or effect, alterations of renal prostaglandin physiology accompanied hypertension in elderly men. No clear alteration of prostaglandin E2 physiology was noted in young male hypertensives.

Acute effects of estradiol on circulating luteinizing hormone and prolactin concentrations and on serotonin turnover in individual brain nuclei

Two experiments tested whether serotonergic neurons participate in the acute feedback effects of estradiol on LH and PRL secretion. In the first study, ovariectomized female rats received oil vehicle or estradiol benzoate and were killed 3 h later. The turnover of serotonin [5-hydroxytryptamine (5-HT)] in microdissected brain nuclei was assessed from its accumulation after monoamine oxidase inhibition. Estradiol treatment produced a gradual rise in PRL and a decline in LH, and potentiated the accumulation of 5-HT in the medial preoptic, ventromedial, and cortical amygdaloid nuclei, suggesting increased turnover. Concentrations of the metabolite, 5-hydroxyindole acetic acid, were also elevated in these areas. 5-HT turnover was unaffected by estradiol in the interstitial nucleus of the stria terminalis, periventricular, dorsomedial, or lateral amygdaloid nuclei. The second experiment tested whether localized 5-HT depletions in these estradiol-activated nuclei blocked the acute effects of the steroid on LH or PRL. Stereotaxic microinjections of the 5-HT neurotoxin, 5,7, dihydroxytryptamine were made into the preoptic area, cortical amygdala, or medial basal hypothalamus in ovariectomized rats, pretreated with desmethylimipramine. Such treatment reduced 5-HT, without affecting catecholamines, in the targeted structures. Localized 5-HT depletion in the preoptic area and amygdala blunted the elevation of PRL, but not the decline of LH, after estradiol. 5-HT depletion in the medial basal hypothalamus elevated, whereas 5-HT depletion in the medial preoptic area lowered, resting levels of LH. These results suggest that: 1) estradiol may acutely increase PRL secretion by activating serotonergic projections to the medial preoptic and cortical amygdaloid nuclei, and 2) serotonergic neurons innervating the preoptic area stimulate LH release, whereas serotonergic systems in the medial basal hypothalamus inhibit LH release.

Evidence that norepinephrine and epinephrine systems mediate the stimulatory effects of ovarian hormones on luteinizing hormone and luteinizing hormone-releasing hormone

Results from previous investigations have suggested an important role for central epinephrine (EPI) systems in mediating the stimulatory effects of ovarian hormones on LH release in ovariectomized female rats. The purpose of these experiments was 1) to test whether selective inhibition of EPI synthesis blocks the sequential accumulation and decline of LHRH concentrations in the median eminence that precedes the ovarian hormone-induced LH surge and 2) to test whether the stimulatory ovarian hormone regimen enhances the activity of EPI systems in the hypothalamus. Ovariectomized rats were treated with estradiol, followed 2 days later by progesterone. Animals were treated before progesterone administration with saline, one of the EPI synthesis inhibitors [SK&F 64139 (2,3-dichloro-tetrahydroisoquinoline HCl) or LY 78335 (dichloro-alpha-methylbenzylamine)], or the dopamine-beta-hydroxylase inhibitor FLA-63 (bis-4-methyl-1-homopiperazinyl thiocarbonyl disulfide), which inhibits NE and EPI synthesis. The catecholamine synthesis inhibitors blocked or delayed the afternoon LH surge. FLA-63 completely prevented the accumulation of LHRH in the median eminence that preceded the rise in LH release. However, selective EPI synthesis inhibition with SK&F 64139 only partially prevented this increase in LHRH. A second EPI synthesis inhibitor, LY 78335, delayed both the LH surge and the rise in LHRH. In a second experiment, the administration of estradiol and progesterone to ovariectomized rats increased the alpha-methyltyrosine-induced depletion of hypothalamic EPI, suggesting increased activity in this system during the LH surge. Further experiments localized this effect to the medial basal hypothalamus. The depletion of both NE and EPI after synthesis inhibition was also enhanced during an earlier period, approximating the time of LHRH accumulation. These results suggest that the ovarian hormones activate both NE and EPI systems to stimulate the early afternoon rise of LHRH in the median eminence and to induce the subsequent LH surge.

Paradoxical elevation of sympathetic activity during catecholamine infusion in rats

Chronic infusion of norepinephrine (NE) or epinephrine in rats by an Alzet osmotic minipump (0.1 mg/kg/hr s.c.) caused a 40 mm Hg increase in systolic blood pressure with no change in heart rate. The administration of chlorisondamine or bretylium, drugs which inhibit sympathetic neuronal function by blocking ganglia and by inhibiting release of neuronal NE, respectively, decreased systolic blood pressure to the same level in NE-infused and vehicle-infused rats whereas heart rate increased only in NE-infused animals. Infusion of NE or epinephrine resulted in a marked elevation in the plasma level of the infused amine and a smaller elevation of its counterpart. Chlorisondamine caused a 30 to 70% reduction in plasma levels of NE and epinephrine during the infusion of these catecholamines. Acute infusion of NE at a rate which caused a slow pressor response was accompanied by an elevation of impulse frequency in the preganglionic cervical sympathetic nerve. In contrast, a faster rate of NE infusion which produced a more rapid pressor response was accompanied by the classical decrease in impulse frequency. These studies demonstrate that the maintenance of elevated blood pressure during catecholamine infusion in rats is dependent upon a paradoxical increase in the activity of the sympathetic nervous system.

Hypertension and cardiovascular hypertrophy during chronic catecholamine infusion in rats

Chronic continuous infusion of norepinephrine (NE) or epinephrine (Epi) subcutaneously in rats resulted in rapid elevation of systolic blood pressure (SBP) by 40 mm Hg. Pressure remained high for the duration of the infusion but rapidly returned to control levels after its termination. Pronounced hypertrophy of the thoracic aorta, abdominal aorta and heart was evident within 2 days of the initiation of NE infusion and a plateau was attained by 5 days of infusion. The activity of tissue ornithine decarboxylase (ODC), the rate limiting enzyme in polyamine biosynthesis, was elevated preceeding the onset of tissue hypertrophy, and returned to control levels coincidentally with the cessation of accelerated tissue growth. It is concluded that high blood pressure in this animal model of hypertension is dependent upon the continued presence of exogenous catecholamine, and that pronounced cardiovascular hypertrophy per se is not sufficient to maintain the hypertension. The elevation and decline of vascular ODC activity is consistent with reports that in other tissues an elevation of ODC activity is an obligatory early event in hypertrophy.

Growth and characterization of normal human urothelium in vitro

A method for initiating rapidly growing cultures of normal human transitional cells from ureter and embryonic bladder specimens has been developed and quantified. A new microdissection technique was used to nonenzymatically separate the urothelium. The use of enriched medium containing 10 micrograms/ml insulin, 5 micrograms/ml transferrin, and 1 microgram/ml hydrocortisone resulted in improved growth. The use of thin collagen gel substrates (0.6 ml/60 mm petri dish) resulted in 97% attachment of explants compared to 77% attachment on plastic. Explants grown on thicker collagen (2 ml/60 mm petri dish) showed, in addition to better attachment, enhanced growth of cells as determined both by measurements of colony size and cell density. Cultures of transitional cells that were initiated using explants could be passed three to five times using 0.1% EDTA for dispersion. Autoradiography of [3H]thymidine-labeled cells showed an initial phase of rapid cell division in primary explant cultures and restimulation of cell division in passaged cultures. Transmission electron microscopy showed that the cells growing out from the explants were continuous with the stratified urothelium maintained in the original explant. Stratification of transitional cells occurred in cultures of both ureter and embryonic bladder cells. Surface cells were joined near their apices by junctional complexes. Desmosomes and Golgi vesicles were present in all cells. Passage in culture did not alter the morphological characteristics of cells.

Fibronectin in evolution: presence in invertebrates and isolation from Microciona prolifera

Fibronectin is found in the tissues of a series of vertebrates and invertebrates which suggests its appearance with the simplest multicellular organisms. Fibronectin is specifically localized on the surface and on the substrate in the immediate vicinity of some, but not all, dissociated Microciona prolifera cells, suggesting that the expression of fibronectin in this organism might be dependent on cell type and/or developmental stage. Fibronectin has been partially purified and characterized from intact Microciona prolifera tissue on the basis of its immunological and biochemical properties.

Plasma renin activity during infusion of epinephrine into the celiac and superior mesenteric arteries in dogs

Previous experiments have demonstrated that increments of circulating epinephrine concentration within the physiological range elevate PRA and that this effect apparently is mediated by extrarenal beta-adrenoceptors. The present experiments were designed to test the possibility that the receptors mediating the PRA response to epinephrine are located in the splanchnic region. Accordingly, adult dogs were anesthetized, and catheters were placed for recording blood pressure, withdrawal of blood samples, and collection of urine. Infusion catheters were placed in a femoral vein and in the celiac and superior mesenteric arteries. After a control period, epinephrine was infused for 45 min at a total rate of 25 ng kg-1 min-1 either iv or directly into the celiac and superior mesenteric arteries (12.5 ng kg-1 min-1 into each artery simultaneously). Renal perfusion pressure was kept at the control level during the infusion period by means of an adjustable suprarenal aortic clamp. PRA rose from a mean control plus recovery value of 4.5 +/- 0.9 ng ml-1 h-1 to 8.7 +/- 0.7 ng ml-1 h-1 during iv epinephrine infusion. In contrast, PRA remained unchanged (3.9 +/- 0.8 vs. 4.3 +/- 1.1 ng ml-1 h-1) in response to infusion of epinephrine directly into the celiac and superior mesenteric arteries. The data indicate that the receptors mediating epinephrine-induced increases in PRA are not located in organs perfused by the celiac and superior mesenteric arteries.

Plasma renin activity during infusion of epinephrine into the carotid and vertebral arteries of anesthetized dogs

Previous experiments have demonstrated that increments of epinephrine concentration within the physiological range elevate PRA when epinephrine is infused iv but not when it is infused directly into the renal artery. The present experiments examined whether an elevation of the circulating epinephrine concentration to the head could account for this elevation of PRA by epinephrine. Anesthetized dogs were surgically prepared for blood sampling and blood pressure recording and for the infusion of epinephrine into either a femoral vein (iv) or the carotid and vertebral arteries. After a control period, epinephrine was infused for 45 min at a total rate of 25 ng kg-1 min-1 either iv or into the head vasculature (3.5 ng kg-1 min-1 into each vertebral artery and 9 ng kg-1 min-1 into each carotid artery). PRA (in nanograms per ml h-1) rose from 1.8 +/- 0.5 to 5.9 +/- 1.2 (mean +/- SE) during iv epinephrine infusion. PRA rose similarly (from 1.5 +/- 0.4 to 4.8 +/- 1.8) during epinephrine infusion to the head. The arterial blood epinephrine concentration rose similarly in response to iv and head epinephrine infusions. Furthermore, the changes in hematocrit, heart rate, blood pressure, and plasma potassium concentration were identical regardless of the route of epinephrine infusion. In separate experiments, a smaller infusion of epinephrine infusion. In separate experiments, a smaller infusion of epinephrine directly into the head vasculature at a total rate of 2.5 ng kg-1 min-1 (0.35 ng kg-1 min-1 into each vertebral artery and 0.9 ng kg-1 min-1 into each carotid artery) was without effect on PRA. The data indicate that 1) epinephrine is apparently neither taken up nor degraded by the microcirculation of the head, and 2) the receptors mediating the stimulatory effect of epinephrine on PRA are not located in regions supplied by the carotid and vertebral arteries.

Serotonin turnover in individual brain nuclei: evaluation of three methods using liquid chromatography with electrochemical detection

Liquid chromatography with electrochemical detection and brain microdissection techniques were used to evaluate three methods of studying serotonin turnover in 10 individual brain nuclei. The increase in serotonin (5-HT) and decline in 5-hydroxyindole acetic acid (5-HIAA) after administration of the monoamine oxidase inhibitor, pargyline, as well as the accumulation of 5-hydroxytryptophan (5-HTP) after the L-amino acid decarboxylase inhibitor, m-hydroxybenzylhydrazine, were measured. Serotonin accumulation and 5-HIAA decline could be detected in the n. caudatus, globus pallidus, cortical amygdala, n. interstitialis striae terminalis, n. preopticus medialis, and n. dorsomedialis. Only serotonin accumulation could be accurately assessed in the n. ventromedialis, n. arcuatus, and median eminence. The pattern of increase of serotonin after pargyline varied in different nuclei. There was a linear increase of serotonin over 90 minutes in the caudate, globus pallidus, and ventromedial nucleus and over 60 minutes in the n. preopticus medialis, and cortical amygdala. This contrasted with a maximal increase at 30 minutes in the other nuclei. However, 5-HIAA decline tended to be greatest after 30 minutes in most nuclei. Increases in 5-HTP concentrations after decarboxylase inhibition were not reliably detected in these areas. These results indicate that two nonsteady state methods may be used to evaluate changes in serotonin turnover in selected individual, nonpooled hypothalamic and forebrain nuclei.

Vibration effects on three measures of relaxation

The effect of vibrotactile stimulation on relaxation as measured by EMG recording of the frontalis and trapezius muscles and by subjective report was assessed. It was predicted that low-frequency vibrotactile stimulation (less than 70 Hz) would facilitate muscle relaxation when measured by both EMG frontalis and trapezius recordings and by subjective report. The participants (8 male and 8 female) were randomly assigned to split-plot, before/after design consisting of four between-subjects treatments and one within-subjects treatment (pre- and post-treatment). The between-subjects treatments were footrest vibration, backrest vibration, footrest-backrest vibration combined, and control. The within-subjects treatment included pre- and post-treatment levels. Results of repeated-measures analyses of variance on each set of data yielded a significant change from pre- to posttreatment condition on all EMG and subjective report measures of muscle tension except the control. The utility of using EMG as a measure of relaxation is discussed.

Role of central epinephrine in regulation of anterior pituitary hormone secretion

Hypothalamic regulation of anterior pituitary hormones is thought to be mediated by the release of stimulatory and/or inhibitory peptides that are, in turn, regulated by catecholaminergic neurons. The recent development of selective epinephrine (EPI) synthesis inhibitors has made it possible to disrupt central EPI neurotransmission without affecting norepinephrine or dopamine. These compounds were used in the present investigation to assess the involvement of brain EPI systems in regulation of GH, LH, and prolactin (PRL) in male and ovariectomized female rats. Inhibition of central EPI synthesis (1) inhibited episodic and morphine-, but not clonidine-induced GH release, and (2) blocked the LH surge induced by estrogen and progesterone, but did not affect episodic LH release in hormonally untreated rats. Inhibition of peripheral (adrenal) EPI synthesis had no effect on these hormones. Results of these studies suggest an excitatory role for EPI in regulation of GH and LH secretion, mediated by stimulation of GH-releasing hormone and LHRH, respectively. EPI does not appear to have a major function in regulation of PRL secretion.

Regulation of episodic growth hormone secretion by the central epinephrine system. Studies in the chronically cannulated rat

Catecholamines are postulated to regulate growth hormone (GH) secretion by their influence on the release of two hypothalamic substances, somatostatin, which inhibits GH release, and GH-releasing factor, as yet unidentified. Extensive pharmacologic studies in man and animals indicate a stimulatory effect of central norepinephrine and dopamine on GH, but the function of epiphephrine (EPI) is uncertain. Furthermore, many of the agents used to study the role of catecholamines in GH regulation are not selective in that they affect adrenergic as well as nor-adrenergic and/or dopaminergic neurotransmission. In the present investigation, central nervous system (CNS) EPI biosynthesis was selectively interrupted with the specific norepinephrine N-methyltransferase inhibitors, SK & F 64139 (Smith, Kline & French Laboratories) and LY 78335, (Eli Lilly & Co. Research Laboratories) and the effects of central EPI depletion on episodic GH secretion in the chronically cannulated rat model were determined. Inhibition of CNS EPI synthesis with SK & F 64139 caused complete suppression of episodic GH secretion and concomitantly reduced the EPI level in the hypothalamus without affecting dopamine or norepinephrine. Administration of LY 78335 produced similar effects on pulsatile GH. Morphine-induced, but not clonidine-induced, GH release also was blocked by SK & F 64139. These results indicate that (a) the central EPI system has a major stimulatory function in episodic GH release, (b) morphine-induced GH release is mediated by the central EPI system, and (c) clonidine stimulates GH release by activation of postsynaptic alpha-adrenergic receptors. Drugs that affect CNS adrenergic systems have a potential role in the diagnosis and treatment of disorders of GH secretion.

Circulating catecholamines in control of renal electrolyte and water excretion

Graded physiological doses of norepinephrine or epinephrine were infused either intravenously or directly into the renal artery of conscious dogs previously prepared with chronic indwelling catheters. Infusion rates ranged from 5 to 125 ng . kg-1 . min-1, and aortic plasma catecholamine concentrations were measured during intravenous infusion to determine the actual levels achieved. Even when the renal arterial plasma norepinephrine concentration was raised to 5,000 pg/ml by either intravenous or intrarenal infusion, only a modest sodium and potassium retention was observed. Only intravenous norepinephrine increased urinary flow rate. Increments of epinephrine concentration from 120 to 2,000 pg/ml decreased sodium and potassium excretion only when delivered intravenously. The concentrations of norepinephrine or epinephrine required to alter urinary sodium and potassium excretion and flow rate were in the upper physiological range or higher and the responses were small except for intravenous epinephrine, which decreased sodium excretion at very low physiological concentrations (120-400 pg/ml). We conclude that circulating epinephrine may play an important physiological role in renal sodium conservation. This effect of epinephrine is not due to a direct intrarenal mechanism.

Plasma epinephrine and control of plasma renin activity: possible extrarenal mechanisms

Previous work from our laboratory has shown that physiological increments of circulating epinephrine concentration increase plasma renin activity (PRA) by an extrarenal beta-receptor mechanism. In the present experiments, epinephrine was infused intravenously at 125 ng.kg-1.min-1 for 45 min in trained, conscious dogs. PRA rose 3 to 5-fold, as previously described, and was accompanied by a transient decline of mean arterial pressure, decreased plasma potassium concentration, and increased hematocrit. Prior splenectomy to maintain hematocrit constant did not attenuate the PRA response to epinephrine. The kidneys of 4 dogs were denervated and constrictor cuff was placed around the renal artery. Renal denervation did not alter the PRA response to intravenous epinephrine infusion. A transient decline in renal perfusion pressure produced by cuff constriction only transiently increase PRA. Neither maintenance of a constant plasma potassium concentration nor oral administration of indomethacin altered the PRA response to epinephrine. We conclude that intravenous epinephrine increases PRA by a mechanism independent of the renal nerves, changes in renal perfusion pressure, hematocrit, plasma potassium concentration, and plasma prostaglandins.