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I S Edelman

Publications and source records attributed to I S Edelman.

At least 73 records · Page 4Linked to original sources
PubMed1979

Thyroid thermogenesis in adult rat hepatocytes in primary monolayer culture: direct action of thyroid hormone in vitro.

We have studied the effect of 3,5,3'-triiodothyronine (T3) on the respiration of adult rat hepatocytes in primary monolayer culture prepared from hypothyroid rat liver. After addition of T3 to the culture medium at a concentration of 2 x 10(-7) M, oxygen consumption of the cultured cells increased detectably at 24 h and was maximal at 72--96 h, relative to control cultures (38.0 +/- 1.8 vs. 25.0 +/- 1.5 microliter/h.mg protein). The thyroid-responsive enzymes, Na+ + K+-activated adenosine triphosphatase (NaK-ATPase) and alpha-glycerophosphate dehydrogenase (GPD), each exhibited increased activity in response to T3, in parallel with the change in oxygen consumption, whereas the activity of Mg-dependent ATPase was unaffected. These responses to T3 were dose dependent over similar concentration ranges, the half-maximal response for each occurring at ca 8 x 10(-10) M. In thyroid-treated cells, the observed increase in respiration was almost completely (90%) inhibited after addition of ouabain (10(-3) M) to the culture medium. It was found also that a 4-h exposure of the cultured hepatocytes to T3 was sufficient to elicit a significant thermogenic response, measured at a time (48 h later) when T3 was no longer present in the medium. The response to T3 occurred in fully defined culture medium and was independent of the presence or absence of hypothyroid rat serum, corticosterone, or insulin, and cellular ATP was unaffected by T3 in concentrations up to 2 x 10(-7) M. The findings document that adult rat hepatocytes in primary monolayer culture respond directly to thyroid hormone; the increases in respiration and NaK-ATPase activity elicited by T3 were cotemporal and apparently coordinate.

Animals↗
PubMed1979

The role of sodium transport in thyroid thermogenesis.

The hypothesis that augmentation of Na+ transport activity mediates a significant fraction of thyroid thermogenesis is supported by studies on a wide range of target tissues. Recent criticisms based on theoretical and experimental considerations do not appear to negate the validity of this concept. A basic difficulty that remains to be resolved, however, is the development of techniques for assessing the contribution of the Na+ transport pathway to energy turnover in the intact animal.

Animals↗
PubMed1978

Effect of aldosterone on incorporation of amino acids into renal medullary proteins.

Studies on the effects of pretreatment with aldosterone on the incorporation of 3H leucine or 3H methionine into proteins in renal slices were carried out in Joklik-modified minimal essential medium. Administration of aldosterone (2microgram/100 g body wt) to adrenalectomized rats increased 3H leucine incorporation into trichloroacetic acid insoluble fractions of crude homogenates of cortical slices by 15.5 +/- 0.4% and of medullary slices by 53.5 +/- 1.3%. No increase in isotope incorporation was observed in slices of renal papilla or spleen prepared from the same rats. Aldosterone had no effect on the 3H-leucine content of the trichloroacetic acid-soluble fractions of all three renal zones and the spleen. The dose of aldosterone that elicited a half-maximal increase in 3H-methionine incorporation into proteins of renal medullary slices (0.45 microgram of aldosterone/100 g body wt) was indistinguishable from that needed to elicit a halt-maximal increase in the urinary K+/Na+ ratio (0.35 microgram of aldosterone/100 g body wt). Dexamethasone, a potent glucocorticoid, at a dose of 0.8 microgram/100 g body wt did not augment 3H-leucine incorporation into renal medullary proteins but was effective at 8 microgram/100 g body wt. Spirolactone (SC-26304), a potent anti-mineralocorticoid, abolished the effect of aldosterone on amino acid incorporation into medullary proteins when administered at a 100-fold higher dosage [i.e., 80 microgram (per 100 g body wt)]. These results imply that the action of aldosterone on amino acid incorporation is mediated by the mineralocorticoid rather than the glucocorticoid pathway, presumably the mineralocorticoid receptors. Moreover, pretreatment of the rats with actinomycin D (70--80 microgram/100 g body wt) erased the effect of aldosterone (0.8 microgram/100 g body wt) on amino acid incorporation into medullary proteins. In paired experiments with 3H and 35S methionine, aldosterone (0.8 microgram/100 g body wt) increased methionine incorporation into trichloroacetic acid precipitable proteins of subcellular fractions of the renal medulla. The effect of aldosterone on incorporation of methionine into medullary cytosol proteins was analyzed further by polyacrylamide gel electrophoresis at pH 8.3 in tris-glycine buffer. The gel profiles indicate that aldosterone significantly increased methionine incorporation into at least one protein (independent of the isotope) with a molecular weight of approximately 31,000. This increase was inhibited by either pretreatment of the rat with actinomycin D (70--80 microgram/100 g body wt or SC-26304 (80 microgram/100 g body wt). Dexamethasone (0.8 microgram/100 g body wt) did not increase incorporation of methinine into the medullary cytosol proteins resolved by polyacrylamide gel electrophoresis.

Adrenalectomy↗
PubMed1978

Induction of citrate synthase by aldosterone in the rat kidney.

The possible induction of renal citrate synthase (E.C. 4.1.3.7) by aldosterone was evaluated in the adrenalectomized rat. Three hours after administration of aldosterone (0.8 microgram/100 g body wt), renal cortical and medullary citrate synthase activity was significantly increased as reported previously by Kinne and Kirsten (Kinne, R., Kirsten, R. 1968. Pfleugers Arch. 300:244). In contrast, no change in this activity was detected in the renal papilla or the liver, under the same conditions. Kinetic analysis revealed that injection of aldosterone had no effect on the KmS for acetyl-CoA and oxalacetate but augmented Vmax of renal medullary citrate synthase activity by 40%. The aldosterone-dependent increase in medullary citrate synthase activity was proportionate to the associated increase in the quantity of antiserum (specific for citrate synthase) required for half-maximal immuno-precipitation. The possibility that aldosterone induced the synthesis of citrate synthase was evaluated in two sets of experiments. In the first set, adrenalectomized rats were injected intraperitoneally with either aldosterone (0.8 microgram/100 g body wt) or the diluent, and simultaneously with 3H or 35S methionine (500 muCi/rat). The isotopes were reversed in about half of the experiments. Three hours after the injection, renal citrate synthase was isolated by ATP-sepharose column chromatography and immuno-precipitation with the specific antiserum. Aldosterone augmented methionine incorporation into renal citrate synthase by 55% but had no effect on incorporation into the hepatic enzyme. In the second set, adrenalectomized rats were injected with either aldosterone (0.8 microcram/100 g body wt) or the diluent, the kidneys were removed 1 hr later and medullary slices were incubated in either 3H- or 35S-methionine at 20 degrees for 2 hr. Mitochondrial citrate synthase was isolated either by ATP-sepharose column chromatography and immuno-precipitation, or by polyacrylamide gel electrophoresis. Aldosterone increased methionine incorporation into the immuno-precipitates by 30% and into the enzyme peak resolved by polyacrylamide gel electrophoresis by 43%. The latter increase was eliminated by prior administration of either actinomycin D (70--80 microgram/100 g body wt) or spirolactone (SC-26304) (80 microgram/100 g body wt). An equimolar dose of dexamethasone (0.8 microgram/100 g body wt) had no effect on the isotope ratio associated with citrate synthase activity in the polyacrylamide gels.

Acetyl Coenzyme A↗
PubMed1978

Occupancy of aldosterone binding sites in rat kidney cytosol.

The binding sites for aldosterone and a potent aldosterone antagonist (SC-26304) were studied in kidney cytosol from adrenalectomized rats. Preformed cytosol and kidney slices were incubated with 3H-labeled steroids in a wide range of concentrations. The recovery and characteristics of the binding sites were affected by the incubation and homogenization conditions. High-affinity, Type I mineralocorticoid binding was reduced by more than 95% when cytosol was incubated at 25 degrees C in the presence of calcium. Tissue dilution also affected the binding sites. SC-26304 was bound to high- and low-affinity receptors, similar to the binding of aldosterone. The physiologic response to aldosterone could result from binding to either or both sets of sites. Some of the physiologic responses to spirolactones could represent antagonism of the binding of aldosterone to either or both sites. A convenient method is presented for describing the relative occupancy of several different sites by any particular steroid.

Adrenalectomy↗
PubMed1978

Binding of aldosterone to cytoplasmic and nuclear receptors of the urinary bladder epithelium of Bufo marinus.

Binding of aldosterone to cytoplasmic and nuclear sites in urinary bladder epithelia of Bufo marinus (Dominican variant) is saturable and dependent upon steroid concentration. Scatchard analysis of specific cytoplasmic binding yielded a maximal binding capacity (N) of 14.5 X 10(-14) mol/mg protein and an apparent equilibrium dissociation constant (Kd) of 1.4 X 10(-8) M. Since Scatchard analysis of specific nuclear binding was complex, this binding was resolved by a computer-generated cirve-fitting technique which analyzed total aldosterone bound. Nuclear binding was resolved into three sites: a nonsaturable site that was linearly dependent upon aldosterone concentration, and two saturable sites (types I and II). Type I sites had relatively low capacity for aldosterone (N = 31 +/- 1 X 10(-14) mol/mg DNA) and high affinity (Kd = 2.5 +/- 0.5 X 10(-9 M); tffininty (Kd = 8.6 +/- 1.7 X 10(-7) M). Competition for [3H]aldosterone binding by dexamethasone, corticosterone, cortisol, progesterone, testosterone, and 17 beta-estradiol demonstrated that type I nuclear sites have higher affinity for aldosterone than for other steroids. The findings are consistent with the inference that the type I site is the mineralocorticoid receptor.

Aldosterone↗
PubMed1978

Aldosterone receptor occupancy and sodium transport in the urinary bladder of Bufo marinus.

The concentration dependence of binding of [3H]aldosterone to cytoplasmic and nuclear receptors was evaluated in urinary bladder epithelial cells of Colombian toads. One class of specific sites (sensitive to displacement by excess aldosterone) was detected in the cytosol. However, two classes of specific nuclear [3H]aldosterone binding sites were evident. In the nucleus, high-affinity (Kd = 2.7 X 10(-9) M), low-capacity (N = 15 X 10(-14) mol/mg DNA) sites (type I) were completely saturated at approximately 4 X 10(-8) M aldosterone, a concentration which gave a maximal increase in short-circuit current (SCC). Occupancy of low-affinity (Kd = 4.6 X 10(-7) M), high-capacity sites (N = 150 X 10(-14) mol/mg DNA) (type II) occurred at higher steroid concentrations and did not correlate with further increase in SCC. Binding parameters of Colombian and Dominican variants of Bufo marinus were compared. In both variants, the SCC increase elicited by aldosterone correlated with accumulation of type I complexes in the nucleus, but the relationship was markedly nonlinear. Various alternatives were considered as the basis for a curvilinear dependence of the increment in Na+ transport on abundance of nuclear type I complexes.

Aldosterone↗
PubMed1978

Further studies on the role of calcium in glucocorticoid-induced lymphocytolysis.

In a previous study comparing the effects of triamcinolone acetonide (TA) and a divalent cation ionophore (A23187) on rat thymocytes, we proposed an important contributory role for Ca2+ in glucocorticoid-induced cytolysis. The plausibility of this hypothesis was tested further in thymic lymphocytes (thymocytes) and lymph node lymphocytes (LN-lymphocytes). Thymocytes incubated in a Ca2+-containing medium responded to TA or A23187 with a concentration-dependent decrease in the number of viable cells. TA-induced cytolysis was reduced in Ca-free medium and was equally supported by Ca2+ and Sr2+, but not by Ba2+. A23187-induced cytolysis was supported by Ca2+ greater than Sr2+, but not by Ba2+. Thymocytes were also lysed by increasing concentrations of Ca2+ even in the absence of TA and A23187. LN-Lymphocytes, however, were less sensitive to the cytotoxic effects of Ca2+ under the same conditions. In the presence of Ca2+, thymocytes were lysed to a greater extent than LN-lymphocytes by TA, whereas the sensitivities to A23187-induced cytolysis were the same in both populations. Omission of Ca2+ from the incubation medium inhibited the cytolytic response to TA only in thymocytes. In contrast, A23187-induced cytolysis was impaired in Ca-free medium in both thymocytes and LN-lymphocytes. These observations confirm the previous findings on Ca2+ dependence of glucocorticoid-induced cytolysis in thymocytes. This pathway, however, may not be involved in glucocorticoid-induced cytolysis of LN-lymphocytes. Thus, a more basic and as yet undefined mechanism probably mediates the lymphocytolytic process.

Animals↗
PubMed1978

Calcium dependence of ionophore A23187-induced lymphocyte cytotoxicity.

Concentrations of the divalent cation ionophore, A23187, optimal for the transformation of human and pig lymphocytes, were cytotoxic to lymphocytes from rats and mice. The biochemical effects associated with A23187-induced cytolysis in rat thymocytes included inhibition of [3H]uridine uptake and incorporation into macromolecules and stimulation of [14C]-alpha-aminoisobutyric acid uptake. The biochemical effects, as well as the reduction in the number of viable cells, were dose dependent and were blocked by the omission of ionic calcium from the incubation medium. At a given ionophore concentration, the magnitude of lysis of thymocytes was proportional to the concentration of Ca2+ in the extracellular medium. Sr2+ was less effective than was Ca2+ in supporting A23187-induced thymocyte lysis. A comparison of the lytic response of lymphocytes of various origins showed that extracellular Ca2+ plays a role in ionophore-induced cytolysis in thymocytes and lymph node lymphocytes but not in mouse lymphosarcoma P1798 cells.

Aminoisobutyric Acids↗
PubMed1977

Spironolactone antagonism of aldosterone action on Na+ transport and RNA metabolism in toad bladder epithelium.

In earlier studies, aldosterone increased the incorporation of precursors into a class of cytoplasmic RNA with the characteristics of messenger RNA (mRNA), in toad bladder epithelium. In the present studies, this effect was analyzed further with a competitive antagonist, spironolactone (SC-9420). Paired hemibladders were labeled with 3H-uridine (30 min pulse - 140 min chase), with or without aldosterone (3.5 x 10(-8) M, 7 X 10(-8) M) in the presence or absence of SC-9420 (7 X 10(-6) M, 2.5 X 10(-5) M) at molar ratios of 200:1 to 280:1. Cytoplasmic RNA, either the total phenol-SDS extract or polyadenylated-RNA (poly(A)(+)-RNA) obtained by oligo-deoxythymidylate-cellulose (oligo(dT)-cellulose) chromatography was analyzed in linear 5 -- 20% sucrose gradients. Eight sets of experiments were completed in which the short-circuit current (scc) was monitored for 180 min and the incorporation of 3H-uridine (30 min pulse -- 150 min chase) was simultaneously determined on pools of epithelia from 5 to 10 hemibladders. The fractional change in scc correlated linearly with the fractional change in 3H-uridine of 12S cytoplasmic RNA (r=0.95, p less than 0.001). The poly(A)(+)-RNA fraction had no detectable rRNA or tRNA and gave a heterogeneous pattern, typical of mRNA, in the sucrose gradients. In the presence of exogenous aldosterone, SC-9420 inhibited the incorporation of 3H-uridine into poly(A)(+)-RNA (particularly 12S). These results support the inference that induction of mRNA mediates the action of aldosterone on Na+ transport.

Aldosterone↗
PubMed1977

Calcium dependence of glucocorticoid-induced lymphocytolysis.

A potent glucocorticoid, triamcinolone acetonide (9alpha-fluoro-11beta, 16alpha,17alpha, 21-tetrahydroxypregna-1,4-diene-3,20-dione-16,17-acetonide) and a divalent cation ionophore (A23187) had similar effects in vitro on [3H]uridine uptake and on lysis of thymocytes of adrenalectomized rats. Removal of Ca2+ from the medium blunted the cytolytic action of triamcinolone acetonide and virtually eliminated that of A23187. In Ca2+-free media, treatment of the thymocytes for 15 hr with triamcinolone acetonide or A23187 followed by re-introduction of Ca2+ resulted in a rapid decrease in cell survival. Based on the time courses of the responses, triamcinolone acetonide and A23187 evoked proportionate increases in 45Ca uptake and lysis of the thymocytes. These findings implicate enhanced Ca2+ uptake in glucocorticoid-dependent lymphocytolysis.

17-Hydroxycorticosteroids↗