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Biomedical subjects

S Huck

Publications and source records attributed to S Huck.

At least 19 recordsLinked to original sources
PubMed2001

Alternate use of distinct intersubunit contacts controls GABAA receptor assembly and stoichiometry.

GABA(A) receptors are the major inhibitory transmitter receptors in the CNS. Recombinant GABA(A) receptors composed of alpha(1)beta(3)gamma(2) subunits have been demonstrated to assemble as pentamers consisting of two alpha(1), two beta(3), and one gamma(2) subunit. Using truncated and chimeric alpha(1) subunits, we identified the alpha(1)(80-100) sequence as a major binding site for gamma(2) subunits. In addition, we demonstrated its direct interaction with gamma(2)(91-104), a sequence that previously has been identified to form the contact to alpha(1) subunits. The observation that the amino acid residues alpha(1)P96 and alpha(1)H101, which can be photolabeled by [(3)H]flunitrazepam, are located within or adjacent to the alpha(1)(80-100) sequence, indicates that the benzodiazepine binding site of GABA(A) receptors is located close to this intersubunit contact. The observation that alpha(1)(80-100) interacts with gamma(2) but not with beta(3) subunits indicates the existence of an additional beta(3) binding site on alpha(1) subunits. The preferred alternate use of the gamma(2) and beta(3) binding sites in two different alpha(1) subunits of the same receptor ensures the incorporation of only a single gamma(2) subunit and thus, determines subunit stoichiometry of alpha(1)beta(3)gamma(2) receptors. Distinct binding sites and their alternate use can therefore explain how subunits of hetero-oligomeric transmembrane proteins assemble into a defined protein complex.

Amino Acid Sequence↗
PubMed2001

Health education groups for caregivers in an HMO.

The short-term effectiveness of a Health Education Group (HEP) intervention program for spouses of frail older adults was compared to the usual care (UC) offered to the spouses of frail older persons in a staff model health maintenance organization. HEP is a multicomponent group program offered in eight weekly, two-hour group sessions, and ten monthly, two-hour follow-up group sessions. It includes emotion-focused and problem-focused coping strategies, education, and support. One-hundred and five spouses were recruited and randomly assigned to HEP (n = 58) or UC (n = 47). Spouse caregivers and care recipients were assessed within two weeks of intervention and within two weeks after the completion of the eight weekly group meetings. The results indicate that, for caregivers, HEP was more effective than UC in reducing depression, maintaining social integration, increasing effectiveness in solving pressing problems, increasing knowledge of community services and how to access them, changing caregivers' feelings of competence, and the way they respond to the care giving situation. No significant differences, however, were found between care recipients in the two arms of the study on any of the outcome measures.

Aged↗
PubMed2001

Expression of B cell receptor-associated signaling molecules in human lupus.

B cell receptor (BcR) signaling requires a tight regulation of several protein tyrosine kinases and phosphatases, and associated co-receptors. Mounting evidence indicates that abnormal BcR signaling, such as occurs in SHP-1 and Lyn-deficient mice, results in production of pathogenic autoantibodies and lupus-like glomerulonephritis, suggesting that altered signaling thresholds could underlie the development of systemic autoimmunity. To test this hypothesis, we investigated expression of BcR-associated signaling molecules in lymphocytes from patients with systemic lupus erythematosus (SLE) during inactive phases of the disease. We found that the transmembrane regulatory protein tyrosine phosphatase CD45 is expressed at abnormal levels. Strikingly, this reduction persisted during four months of follow-up. By contrast, despite its potent role as a regulator of thymus-independent immune responses and of B cell life span, the CD22 co-receptor is expressed at normal levels in B lymphocytes isolated ex vivo from SLE patients. We also noted unusual levels of the cytosolic protein tyrosine kinase Lyn and the protein tyrosine phosphatase SHP-1 in the lymphocytes of the patients. Since in normal B cells Lyn and SHP-1 act in concert within a common negative pathway in which CD45 counteracts SHP-I regulatory role, we propose that this feedback regulatory pathway is crippled to different degrees in human SLE B cells. Break of the balance between positive and negative signaling molecules likely modifies the BcR signaling thresholds. Such alterations, together with other factors, may contribute to the disruption of self-tolerance in this disease.

Animals↗
PubMed2000

The implementation of the EverCare demonstration project.

EverCare represents a creative approach to providing medical services to long-stay nursing home patients. It offers a capitated package of Medicare-covered services with more intensive primary care provided by nurse practitioners. The program's underlying premise is that better primary care will result in reduced hospital use. This work examines the implementation of the program in six locations. It identifies some of the issues that must be addressed if the program is to succeed both operationally and financially.

Aged↗
PubMed1999

Somatic and prejunctional nicotinic receptors in cultured rat sympathetic neurones show different agonist profiles.

1. The release of [3H]-noradrenaline ([3H]-NA) in response to nicotinic acetylcholine receptor (nAChR) agonists was compared with agonist-induced currents in cultured rat superior cervical ganglion (SCG) neurones. 2. [3H]-NA release in response to high concentrations of nicotinic agonists was reduced, but not fully inhibited, by the presence of either tetrodotoxin (TTX) or Cd2+ to block voltage-gated Na+ or Ca2+ channels, respectively. We used the component of transmitter release that remained in the presence of these substances (named TTX- or Cd2+-insensitive release) to pharmacologically characterize nAChRs in proximity to the sites of vesicular exocytosis (prejunctional receptors). Prejunctional nAChRs were activated by nicotinic agonists with a rank order of potency of dimethylphenylpiperazinium iodide (DMPP) > nicotine > cytisine > ACh, and with EC50 values ranging from 22 microM (DMPP) to 110 microM (ACh). 3. [3H]-NA release in response to low concentrations of nAChR agonists was fully inhibited by the presence of either TTX or Cd2+ (named TTX- or Cd2+-sensitive release). TTX-sensitive release was triggered by nicotinic agonists with a rank order of potency of DMPP > cytisine approximately nicotine approximately ACh, which due to its similarity to TTX-insensitive release indicates that it might also be triggered by prejunctional-type nAChRs. The EC50 values for TTX (Cd2+)-sensitive release were less than 10 microM for all four agonists. 4. By contrast to transmitter release, somatic nAChRs as seen by patch clamp recordings were most potently activated by cytisine, with a rank order of potency of cytisine > nicotine approximately DMPP > ACh. EC50 values for the induction of currents exceeded 20 microM for all four agonists. 5. The nicotinic antagonist mecamylamine potently inhibited all transmitter release in response to nicotine. alpha-Bungarotoxin (alpha-BuTX) was, on the other hand, without significant effect on nicotine-induced TTX-insensitive release. The competitive antagonist dihydro-beta-erythroidine (DHbetaE) caused rightward shifts of the dose-response curves for both TTX-sensitive and TTX-insensitive transmitter release as well as for currents in response to nicotine, with pA2 values ranging from 4.03 to 4.58. 6. Due to clear differences in the pharmacology of agonists we propose that nAChRs of distinct subunit composition are differentially targeted to somatic or axonal domains.

Animals↗
PubMed1999

Analysis of intrachromosomal homologous recombination in mammalian cell, using tandem repeat sequences.

In all the organisms, homologous recombination (HR) is involved in fundamental processes such as genome diversification and DNA repair. Several strategies can be devised to measure homologous recombination in mammalian cells. We present here the interest of using intrachromosomal tandem repeat sequences to measure HR in mammalian cells and we discuss the differences with the ectopic plasmids recombination. The present review focuses on the molecular mechanisms of HR between tandem repeats in mammalian cells. The possibility to use two different orientations of tandem repeats (direct or inverted repeats) in parallel constitutes also an advantage. While inverted repeats measure only events arising by strand exchange (gene conversion and crossing over), direct repeats monitor strand exchange events and also non-conservative processes such as single strand annealing or replication slippage. In yeast, these processes depend on different pathways, most of them also existing in mammalian cells. These data permit to devise substrates adapted to specific questions about HR in mammalian cells. The effect of substrate structures (heterologies, insertions/deletions, GT repeats, transcription) and consequences of DNA double strand breaks induced by ionizing radiation or endonuclease (especially the rare-cutting endonuclease ISce-I) on HR are discussed. Finally, transgenic mouse models using tandem repeats are briefly presented.

Animals↗
PubMed1999

Modulation of spontaneous and stimulation-evoked transmitter release from rat sympathetic neurons by the cognition enhancer linopirdine: insights into its mechanisms of action.

The mechanisms by which the cognition enhancer linopirdine may affect transmitter release were investigated in cultures of rat superior cervical ganglion neurons. Overflow of previously incorporated [3H]noradrenaline evoked by 10 microM UTP or 0.1 microM bradykinin was enhanced by linopirdine at > or =3 microM, overflow evoked by 25 mM K(-), 100 microM nicotine, or 300 microM ATP was enhanced by linopirdine at > or =10 microM, and overflow due to 40 mM K+ or electrical field stimulation was not altered by linopirdine. Ba2+ (0.3 mM) augmented the same types of stimulation-evoked overflow to a similar extent as linopirdine. K+ (25 mM), nicotine (100 microM), and ATP (300 microM) triggered transmitter release in a partially tetrodotoxin-resistant manner, and the release-enhancing action of linopirdine was lost in the presence of tetrodotoxin (1 microM). Linopirdine (10 microM) raised spontaneous tritium outflow and reduced currents through muscarinic K+ (K(M)) channels with a similar time course. The secretagogue action of linopirdine was concentration- and Ca2(+)-dependent and abolished by tetrodotoxin (1 microM) or Cd2+ (100 microM). Linopirdine (10 microM) added to the partial inhibition of K(M) channels by 1 or 3 mM Ba2(+) but not to the complete inhibition by 10 mM Ba2(+). Likewise, the secretagogue action of 1 and 3 mM, but not that of 10 mM, Ba2+ was enhanced by linopirdine. These results indicate that linopirdine facilitates and triggers transmitter release via blockade of K(M) channels and suggest that these K+ channels are located at neuronal somata rather than at presynaptic sites.

Adenosine Triphosphate↗
PubMed1999

Abnormal DNA methylation and deoxycytosine-deoxyguanine content in nucleosomes from lymphocytes undergoing apoptosis.

Systemic lupus erythematosus (SLE) is characterized by an accelerated apoptosis of peripheral lymphocytes and an impairment of the clearance of apoptotic cells. Since changes in DNA methylation and in deoxycytosine and deoxyguanine (GC) content have been shown to enhance the potential of DNA to activate murine and human B lymphocytes, we tested the capacity of lymphocytes undergoing apoptosis (under conditions that mimic the deletion of self-reactive cells after antigen receptor engagement) to generate nucleosomes with a particular base composition. Using two cell culture systems and four apoptosis triggers, we found an increase of deoxymethylcytosine in fragmented chromosomal DNA of apoptotic B and T lymphocytes. However, this increase was not associated with modulation of DNA (cytosine-5) methyltransferase, the enzyme that methylates eukaryotic DNA, which suggests that the changes in DNA methylation patterns are not linked to the process of de novo DNA methylation during cell death. In addition, we could not detect a unique methylation pattern in highly repetitive Alu sequences present in the human genome of SLE subjects, as compared with controls. However, the abnormal DNA methylation of apoptotic nucleosomes was associated with an unusual pattern of nuclease-resistant, GC-rich regions in these DNA fragments. We propose that the combination of an accelerated apoptosis with a defect in the clearance of apoptotic cells results in release of increased amounts of nucleosomes with abnormally methylated, GC-rich DNA and provides an autologous stimulation that could bypass tolerance to self in systemic autoimmune diseases. These findings support the concept that the structure and dynamics of nucleosomes are critical in determining their immunogenicity in SLE.

Animals↗
PubMed1998

High-density expression of CD95 on B cells and underrepresentation of the B-1 cell subset in human lupus.

Recent evidence indicates that B cell receptor signaling plays a role in the generation of the B-1 cell lineage that expresses the CD5 marker, and the CD95-mediated death plays an essential role in maintaining B cell tolerance. We therefore probed CD5 and CD95 expression on B cells from systemic lupus erythematosos (SLE) patients and control subjects. Firstly, in agreement with previous studies, we found that CD5 expression (11%) was relatively constant among control individuals. We also noted that the activation of B cells up-regulates this marker. Unexpectedly, we found that the B-1 cell subset is under-represented (3.9+/-0.3%) in SLE patients in an inactive stage of the disease. Together with related studies, these findings suggest that there is a correlation between CD5 expression and disease activity. Secondly, we found that CD95(+) B cells can be divided into two subsets expressing a high- (CD95(high)) and a low-density (CD95(low)) of CD95. There was no difference in the proportion of total CD95(+) B cells (23.5+/-2.8) in the two groups, but SLE patients in an inactive phase of the disease characteristically expressed a relatively high proportion (50%) of CD95(high) B cells. This finding would mean that a large fraction of B lymphocytes are sensitive to apoptosis, implying that autoantibody-producing B cells are derived from CD95(low) B cells and are relatively resistant to apoptosis.

Adult↗
PubMed1998

Carrier-mediated release, transport rates, and charge transfer induced by amphetamine, tyramine, and dopamine in mammalian cells transfected with the human dopamine transporter.

Amphetamine and related substances induce dopamine release. According to a traditional explanation, this dopamine release occurs in exchange for amphetamine by means of the dopamine transporter (DAT). We tested this hypothesis in human embryonic kidney 293 cells stably transfected with the human DAT by measuring the uptake of dopamine, tyramine, and D- and L-amphetamine as well as substrate-induced release of preloaded N-methyl-4-[3H]phenylpyridinium ([3H]MPP+). The uptake of substrates was sodium-dependent and was inhibited by ouabain and cocaine, which also prevented substrate-induced release of MPP+. Patch-clamp recordings revealed that all four substrates elicited voltage-dependent inward currents (on top of constitutive leak currents) that were prevented by cocaine. Whereas individual substrates had similar affinities in release, uptake, and patch-clamp experiments, maximal effects displayed remarkable differences. Hence, maximal effects in release and current induction were approximately 25% higher for D-amphetamine as compared with the other substrates. By contrast, dopamine was the most efficacious substrate in uptake experiments, with its maximal initial uptake rate exceeding those of amphetamine and tyramine by factors of 20 and 4, respectively. Our experiments indicate a poor correlation between substrate-induced release and the transport of substrates, whereas the ability of substrates to induce currents correlates well with their releasing action.

Amphetamine↗
PubMed1998

Presynaptic inhibition by concanavalin A: are alpha-latrotoxin receptors involved in action potential-dependent transmitter release?

Effects of concanavalin A on transmitter release were investigated in primary cultures of chick sympathetic neurons. The lectin reduced electrically evoked [3H]noradrenaline release by up to 30% with half-maximal inhibition at 0.16 microM. Concanavalin A also reduced the release triggered by extracellular Ca2+ in neurons depolarized by 25 mM K or rendered Ca2+-permeable by the ionophore A23187. The inhibitory action of concanavalin A on electrically evoked release was additive to that of the alpha2-adrenergic agonist UK 14,304. Inactivation of Gs and Gi/Go type G proteins by either cholera or pertussis toxin did not alter the inhibitory effect of the lectin. Concanavalin A failed to affect the resting membrane potential, action potential waveforms, or voltage-dependent K+ and Ca2+ currents. In contrast, the lectin efficiently blocked both the Ca2+-dependent and -independent alpha-latrotoxin-induced transmitter release, but only when applied before the toxin. The reduction of electrically evoked, as well as alpha-latrotoxin-evoked, release by concanavalin A was attenuated in the presence of glucose and abolished by methyl alpha-D-mannopyranoside. The dimeric derivative, succinyl-concanavalin A, was significantly less active than tetrameric concanavalin A. In bovine adrenal chromaffin cells, which displayed only weak secretory responses to alpha-latrotoxin, concanavalin A failed to alter K+-evoked catecholamine secretion. These results show that concanavalin A causes presynaptic inhibition in sympathetic neurons and indicate that cross-linking of alpha-latrotoxin receptors may reduce action potential-dependent transmitter release.

Action Potentials↗
PubMed1997

The IGHG3 gene shows a structural polymorphism characterized by different hinge lengths: sequence of a new 2-exon hinge gene.

Four of the five human IGHG genes (G1, GP, G2, and G4) display a hinge region consisting of a unique exon. In contrast, IGHG3 exhibits a different structure in which the hinge is constituted by four or, less frequently, three exons. We report here the nucleotide sequence of a new 2-exon hinge G3 gene found in a Mandenka individual from Eastern Senegal. A comparison of this sequence with that of 4-exon and 3-exon hinge G3 genes suggests that the 3-exon and 2-exon hinge forms arose independently by deletion events in a 4-exon hinge gene.

B-Lymphocytes↗
PubMed1997

Receptors controlling transmitter release from sympathetic neurons in vitro.

Primary cultures of postganglionic sympathetic neurons were established more than 30 years ago. More recently, these cultures have been used to characterize various neurotransmitter receptors that govern sympathetic transmitter release. These receptors may be categorized into at least three groups: (1) receptors which evoke transmitter release: (2) receptors which facilitate; (3) receptors which inhibit, depolarization-evoked release. Group (1) comprises nicotinic and muscarinic acetylcholine receptors, P2X purinoceptors and pyrimidinoceptors. Group (2) currently harbours beta-adrenoceptors, P2 purinoceptors, receptors for PACAP and VIP, as well as prostanoid EP1 receptors. In group (3), muscarinic cholinoceptors, alpha 2- and beta-adrenoceptors, P2 purinoceptors, and receptors for the neuropeptides NPY, somatostatin (SRIF1) and LHRH, as well as opioid (delta and kappa) receptors can be found. Receptors which regulate transmitter release from neurons in cell culture may be located either at the somatodendritic region or at the sites of exocytosis, i.e. the presynaptic specializations of axons. Most of the receptors that evoke release are located at the soma. There ionotropic receptors cause depolarizations to generate action potentials which then trigger Ca(2+)-dependent exocytosis at axon terminals. The signalling mechanisms of metabotropic receptors which evoke release still remain to be identified. Receptors which facilitate depolarization-evoked release appear to be located preferentially at presynaptic sites and presumably act via an increase in cyclic AMP. Receptors which inhibit stimulation evoked release are also presynaptic origin and most commonly rely on a G protein-mediated blockade of voltage-gated Ca2+ channels. Results obtained with primary cell cultures of postganglionic sympathetic neurons have now supplemented previous data about neurotransmitter receptors involved in the regulation of ganglionic as well as sympatho-effector transmission. In the future, this technique may prove useful to identify yet unrecognized receptors which control the output of the sympathetic nervous system and to elucidate underlying signalling mechanisms.

Animals↗
PubMed1997

Noradrenaline release from rat sympathetic neurones triggered by activation of B2 bradykinin receptors.

1. The role of bradykinin receptors in the regulation of sympathetic transmitter release was investigated in primary cultures of neurones dissociated from superior cervical ganglia of neonatal rats. These cultures were loaded with [3H]-noradrenaline and the outflow of radioactivity was determined under continuous superfusion. 2. Bradykinin (100 nmol l[-1] applied for 10 min) caused a transient increase in tritium outflow that reached a peak within four minutes after the beginning of the application and then declined towards the baseline, despite the continuing presence of the peptide. ATP (100 micromol l[-1]) and nicotine (10 micromol l[-1]) caused elevations in 3H outflow with similar kinetics, whereas outflow remained elevated during a 10 min period of electrical field stimulation (0.5 ms, 50 mA, 50 V cm[-1], 1.0 Hz). 3. When bradykinin was applied for periods of 2 min, the evoked 3H overflow was half-maximal at 12 nmol l(-1) and reached a maximum of 2.3% of cellular radioactivity. The preferential B1 receptor agonist des-Arg9-bradykinin failed to alter 3H outflow. The B2 receptor antagonists, [D-Phe7]-bradykinin (1 micromol l[-1]) and Hoe 140 (10 nmol l[-1]), per se did not alter 3H outflow, but shifted the concentration-response curve for bradykinin-evoked 3H overflow to the right by a factor of 7.9 and 4.3, respectively. 4. Bradykinin-induced overflow was abolished in the absence of extracellular Ca2+ and in the presence of either 1 micromol l(-1) tetrodotoxin or 300 micromol l(-1) Cd2+, as was electrically-induced overflow. Activation of alpha2-adrenoceptors by 1 micromol l(-1) UK 14,304 reduced both bradykinin- and electrically-triggered overflow. The Ca2+-ATPase inhibitor thapsigargin (0.3 micromol l[-1]) failed to alter either type of stimulated overflow. Caffeine (10 mmol l[-1]) enhanced bradykinin-induced overflow, but reduced overflow triggered by electrical field stimulation. 5. Inclusion of Ba2+ (0.1 to 1 mmol l[-1]) in the superfusion medium enhanced electrically induced overflow by approximately 100% and potentiated bradykinin-triggered overflow by almost 400%. Application of 1 mmol l(-1) Ba2+ for periods of 2 min triggered 3H overflow, and this overflow was abolished by 1 micromol l(-1) tetrodotoxin and enhanced by 10 mmol l(-1) caffeine. In contrast, inclusion of tetraethylammonium (0.1 to 1 mmol l[-1]) in the superfusion buffer caused similar increases of bradykinin- and electrically evoked 3H overflow (by about 100%), and tetraethylammonium, when applied for 2 min, failed to alter 3H outflow. 6. Treatment of cultures with 100 ng ml(-1) pertussis toxin caused a significant increase in bradykinin-, but not in electrically-, evoked tritium overflow. Treatment with 100 ng ml(-1) cholera toxin reduced both types of stimulated 3H overflow. 7. These data reveal bradykinin as a potent stimulant of action potential-mediated and Ca2+-dependent transmitter release from rat sympathetic neurones in primary cell culture. This neurosecretory effect of bradykinin involves activation of B2-receptors, presumably linked to pertussis- and cholera toxin-insensitive G proteins, most likely members of the Gq family. Results obtained with inhibitors of muscarinic K+ (KM) channels, like caffeine and Ba2+, indicate that the secretagogue action of bradykinin probably involves inhibition of these K+ channels.

Adrenergic alpha-Agonists↗
PubMed1996

Involvement of a phorbol ester-insensitive protein kinase C in the alpha2-adrenergic inhibition of voltage-gated calcium current in chick sympathetic neurons.

alpha2-Adrenoceptors regulate the efficacy at the sympathoeffector junction by means of a feedback inhibition of transmitter release. In chick sympathetic neurons, the mechanism involves an inhibition of N-type calcium channels, and we now present evidence that this effect involves an atypical, phorbol ester-insensitive protein kinase C (PKC). The inhibition of voltage-gated Ca2+ currents by the specific alpha2-adrenergic agonist UK 14,304 was significantly attenuated when the PKC inhibitors PKC(19-36), staurosporine, or calphostin C were included in the internal solution used to fill the patch pipettes, or if staurosporine or calphostin C were applied extracellularly; however, phorbol esters as classical activators of PKC or oleoylacetylglycerol did not mimic the effect of UK 14,304, and chronic exposure to 4-beta-phorbol dibutyrate (PDBu) did not attenuate it, ever though PKCalpha and -epsilon isozymes were translocated to plasma membranes by PDBu. The atypical isozyme PKCzeta was translocated by 100 micrometer AA and this effect was attenuated when PKC(19-36) was added to the patch pipette solution. Our observations indicate that classical, new, and atypical PKC isozymes are present in chick sympathetic neurons and that an atypical, phorbol ester-insensitive PKC is involved in the inhibition of voltage-activated calcium currents by alpha2-adrenoceptor activation.

Animals↗
PubMed1996

Synthesis and calcium antagonistic activity of 8-[N-[2-(3,4-dimethoxy- phenyl)ethyl]-beta-alanyl]-5,6,7,8-tetrahydrothieno[3,2-b][1,4]thiazepi ne fumarate.

KT-362 is an antiarrhythmic and antihypertensive agent with vasodilating activity. Since it carries a homoveratryl group in the side chain, an obvious relation exists to the verapamil-type calcium antagonists. Replacement of the fused aromatic moiety in KT-362 with thiophene provided 8-[N-[2-(3,4-dimethoxyphenyl) ethyl]-beta-alanyl]-5,6,7,8-tetrahydrothieno[3,2-b][1,4] thiazepine (1). Compound 1 shows a negative chronotropic activity in spontaneously beating right atria (IC50 = 23 microM, n = 7), and a negative inotropic effect in papillary muscles (IC50 = 2.7 microM, n = 7) and left atria (IC50 = 4 microM, n = 6) of the guinea-pig heart. The decrease of contractility in papillary muscles could be antagonized by increasing the extracellular calcium concentration. Compound 1 was found to affect high (IC50: 70 +/- 5 microM) and low (IC50: 129 +/- 34 microM) voltage-activated calcium channel currents as well as voltage-activated sodium channel currents (IC50: 80 +/- 13 microM) in chick dorsal root ganglion neurons. In addition nicotine-induced currents were potently inhibited (IC50: 6 +/- 0.7 microM) in bovine chromaffin cells.

Animals↗