Beta-Adrenergic Stimulation of Cyclic AMP Content and Parathyroid Hormone Release from Isolated Bovine Parathyroid Cells**

Brown, Edward M.; Hurwitz, Samuel H.; Aurbach, G. D.

doi:10.1210/endo-100-6-1696

Cited by 126 publications

(39 citation statements)

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“…It is known that the beta agonist isoproterenol, at concentrations between 1 and 10 gym, increases PTH secretion rate in dispersed bovine parathyroid cells (Brown et al ., 1977). We have studied the effects of variable concentrations of isoproterenol (between 10 and 40 uM) added to the modified Krebs solution in four cells whose electrical response to external Ca" had previously been observed.…”

Section: Effects Of Isoproterenolmentioning

confidence: 99%

“…intracellular cAMP (Brown et al, 1977 ;Fischer et al, 1982). This correspondence between membrane voltage and secretion contrasts with the usual sequence of events found in other glands, where the physiological stimulants for secretion evoke a membrane depolarization that opens voltage-dependent Ca" channels .…”

Section: Relationship Between Membrane Electrical Events and Pth Secrmentioning

confidence: 99%

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Depolarizing response of rat parathyroid cells to divalent cations.

López‐Barneo¹,

Armstrong²

1983

The Journal of General Physiology

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Membrane potentials were recorded from rat parathyroid glands continuously perfused in vitro. At 1 .5 mM external Ca", the resting potential averages -73 ± 5 mV (mean ± SD, n = 66). On exposure to 2.5 mM Ca", the cells depolarize reversibly to a potential of -34 ± 8 mV (mean ± SD). Depolarization to this value is complete in^-2-4 min, and repolarization on return to 1 .5 mM Ca" takes about the same time . The depolarizing action of high Ca" is mimicked by all divalent cations tested, with the following order of effectiveness: Ca" > Sr" > Mg" > Ba++ for alkali-earth metals, and Ca" > Cd++ > Mn++ > Co' > Zn ++ for transition metals . Input resistance in 1 .5 mM Ca" was 24 .35 ± 14 MQ (mean ± SD) and increased by an average factor of 2.43 ± 0 .8 after switching to 2.5 mM Ca++ . The low value of input resistance suggests that cells are coupled by low-resistance junctions. The resting potential in low Ca' is quite insensitive to removal of external Na+ or Cl -, but very sensitive to changes in external K+ . Cells depolarize by 61 mV for a 10=fold increase in external K+ . In high Ca+ +, membrane potential is less sensitive to an increase in external K+ and is unchanged by increasing K+ from 5 to 25 mM . Depolarization evoked by high Ca' may be slowed, but is unchanged in amplitude by removal of external Na+ or Cl-. Organic (13600) and inorganic (Co++, Cd++ , and Mn++) blockers of the Ca' channels do not interfere with the electrical response to Ca" changes. Our results show remarkable parallels to previous observations on the control of parathormone (PTH) release by Ca". They suggest an association between membrane voltage and secretion that is very unusual: parathyroid cells secrete when fully polarized, and secrete less when depolarized. The extraordinary sensitivity of parathyroid cells to divalent cations leads us to hypothesize the existence in their membranes of a divalent cation receptor that controls membrane permeability (possibly to K+) and PTH secretion .

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Section: Effects Of Isoproterenolmentioning

confidence: 99%

Section: Relationship Between Membrane Electrical Events and Pth Secrmentioning

confidence: 99%

Depolarizing response of rat parathyroid cells to divalent cations.

López‐Barneo¹,

Armstrong²

1983

The Journal of General Physiology

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“…We recently described the preparation of viable dispersed bovine parathyroid cells which retain many of the morphologic and functional properties recognized physiologically (12). We now show that this cell preparation contains a dopamine receptor that is unequivocally differentiated from the ,B-adrenergic receptor previously identified in this tissue (13)(14)(15)(16). Alterations in cellular cAMP correlate directly with changes in parathyroid hormone (PTH) release, the biologic consequence of increased cAMP in this cell type.…”

mentioning

confidence: 65%

“…Cell viability (trypan blue exclusion) was routinely 95-100%. Reagents were of the best grade commercially available and were obtained from sources previously cited (13 The accumulation of cAMP in response to 1 MuM dopamine was inhibited by the potent phenothiazines fluphenazine and chlorpromazine with 50% inhibition concentrations (IC50) of about 0.1 and 0.3 ,M (Fig. 3).…”

Section: Methodsmentioning

confidence: 99%

Dopaminergic stimulation of cyclic AMP accumulation and parathyroid hormone release from dispersed bovine parathyroid cells

Brown

Carroll

Aurbach

1977

Proc. Natl. Acad. Sci. U.S.A.

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The effects of dopaminergic agonists and antagonists have been studied in dispersed bovine parathyroid cells. Dopaminergic agonists caused a transient 20-to 40-fold increase in cellular cyclic AMP and a 2-to 3fold increase in parathyroid hormone release. Dose-response relationships were similar for cyclic AMP accumulation and hormone release, whether studied by increasing agonist concentration or by increasing concentration of antagonist with constant agonist. The effects on the dopamine receptor could be differentiated from those of the previously characterized f3-adrenergic receptor by specific inhibitors. These results appear to represent proof with a homogeneous cell population that dopaminergic receptors linked to adenylate cyclase can regulate a secretory process mediated by cyclic AMP. This system should be useful in further studies on In most of these studies, preparations from heterogeneous cell populations represented by whole organs, tissue slices, homogenates, or membrane fractions had been used, and functional capacity of the cells had not been determined. Thus, it has been difficult to correlate alterations in biological function directly with changes in cAMP, the presumed intracellular mediator of these effects. We recently described the preparation of viable dispersed bovine parathyroid cells which retain many of the morphologic and functional properties recognized physiologically (12). We now show that this cell preparation contains a dopamine receptor that is unequivocally differentiated from the ,B-adrenergic receptor previously identified in this tissue (13)(14)(15)(16). Alterations in cellular cAMP correlate directly with changes in parathyroid hormone (PTH) release, the biologic consequence of increased cAMP in this cell type. Dispersed bovine parathyroid cells thus provide a useful model for studying the interaction of dopaminergic agonists and antagonists with target tissues. MATERIALS AND METHODSDispersed bovine parathyroid cells were prepared as described (12) by digestion with collagenase and DNase. Incubations were carried out in 20-ml polypropylene scintillation vials (Beckman) in a 370 metabolic shaker (Dubnoff-Precision Scientific Instruments); the medium was Eagle's medium number 2 (bicarbonate deleted) supplemented with 0.02 M N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (Hepes) (pH 7.47), 0.5 mM MgSO4, variable CaCl2 as indicated, and 0.2% heatinactivated bovine serum albumin ("standard medium"). Agonists and antagonists were added directly to the cell suspension (100,000-400,000 cells per ml). In time-course experiments, separate vials were used for each time point.Medium was separated from cells in 400-,g Microfuge tubes (Beckman) and assayed for PTH with a guinea pig anti-bovine-PTH antiserum (12). cAMP was extracted with 5% (wt/vol) perchloric acid, neutralized with potassium bicarbonate, acetylated, and determined by radioimmunoassay with a modification of the method of Harper and Brooker (17). In several experiments, intracellular and extracellular cAMP...

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“…The wet mycelium was removed, placed in 5 ml cold 7% (v/v) HC104, homogenized with an Ultra-Turrax homogenizer, and centrifuged at 12000g for 10 rnin at 4 "C. The supernatant was neutralized with 2 M-KHCO,. After a second centrifugation, samples were acetylated and azsayed by radioimmunoassay according to the modifications of Gardner et al (1978) and Brown et al (1977) of the method of Harper & Brooker (1975). The antibody-bound fraction was separated from the free ligand using Staphylococcus aureus (Bar & Hurwitz, 1979).…”

Section: R S H a P I R A A N D O T H E R Smentioning

confidence: 99%

Regulation of Glycogen Synthase in Sclerotium rolfsii

et al. 1986

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765Changes in glycogen, extracellular polysaccharides, glycogen synthase (EC 2.4.1 . 1 1) and cAMP were followed during growth of submerged mycelium of Sclerotium rolfsii. While glucose was present in the medium glycogen and extracellular polysaccharides accumulated to maximum levels of 40 pg (mg dry wt)-l and 0-3 mg (mg dry wt)-l respectively; they were degraded following glucose exhaustion. Neither glycogen nor extracellular polysaccharide concentrations were affected by increasing the glucose concentration in the growth medium from 0.5 to 1-5 % (w/v). Following inoculation, both glucose-6-phosphate-dependent and glucose-6-phosphate-independent glycogen synthase activities increased during exponential growth, remained constant during the stationary phase as long as glucose was present in the medium, and declined rapidly after the exhaustion of glucose. The cAMP content of submerged cultures of S . rolfsii was 5 pmol (mg protein)-' ; however, upon glucose exhaustion there was a sharp increase followed by a decrease to the initial basal level. The activity of glycogen synthase in crude extracts was increased by glucose 6-phosphate and inhibited by CAMP.

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Beta-Adrenergic Stimulation of Cyclic AMP Content and Parathyroid Hormone Release from Isolated Bovine Parathyroid Cells**

Cited by 126 publications

References 0 publications

Depolarizing response of rat parathyroid cells to divalent cations.

Depolarizing response of rat parathyroid cells to divalent cations.

Dopaminergic stimulation of cyclic AMP accumulation and parathyroid hormone release from dispersed bovine parathyroid cells

Regulation of Glycogen Synthase in Sclerotium rolfsii

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