Papers by Adrian Sculptoreanu
Developments in Cardiovascular Medicine, 1994
Nature International Weekly Journal of Science, 1993
Journal of Pharmacology and Experimental Therapeutics, Jul 1, 1998
The myocardial effects of alpha-1A adrenoceptor (alpha-1 AR) agonists in neonatal rats are mediat... more The myocardial effects of alpha-1A adrenoceptor (alpha-1 AR) agonists in neonatal rats are mediated by alpha-1A AR and not by alpha-1B AR, although both receptor subtypes are equally expressed; the functions of alpha-1B AR are not known. Here, we report that alpha-1B ARs inhibit the activities of alpha-1A ARs in neonatal rat myocardium so that the inactivation of alpha-1B ARs by chloroethylclonidine (CEC) potentiated the effects of nonselective alpha-1 AR agonist phenylephrine (PE) on myocardial protein synthesis and early gene (c-fos and c-jun) expression. CEC did not modify the hypertrophic effect of angiotensin II. The potentiation of the effects of PE by CEC was associated with a translocation of Ca ϩϩ -dependent protein kinase C (PKC)␣, which did not occur in the absence of CEC. Alpha-1A AR-selective agonist A61603 was ϳ1000-fold more potent than PE as a positive inotropic agent; it caused the translocation of PKC␣, which was not affected by CEC.
Can J Physiol Pharmacol, 2003
L-type Ca 2+ channels are essential in triggering the intracellular Ca 2+ release and contraction... more L-type Ca 2+ channels are essential in triggering the intracellular Ca 2+ release and contraction in heart cells. In this study, we used patch clamp technique to compare the effect of two pure enantiomers of L-type Ca 2+ channel agonists: (+)-CGP 48506 and the dihydropyridine (+)-SDZ-202 791 in cardiomyocytes from rats 2-5 days old. The predominant Ca 2+ current activated by standard step pulses in these myocytes was L-type Ca 2+ current. The dihydropyridine antagonist (+)-PN200-110 (5 µM) blocked over 90% of Ca 2+ currents in most cells tested. CGP 48506 lead to a maximum of 200% increase in currents. The threshold concentration for the CGP effect was at 1 µM and the maximum was reached at 20 µM. SDZ-202 791 had effects in nanomolar concentrations and a maximum effect at about 2 µM. The maximal effect of (+)-SDZ-202 791 was a 400% increase in the amplitude of Ca 2+ currents and was accompanied by a 10-15 mV leftward shift in the voltage dependence of activation. CGP 48506 increased the currents equally at all voltages tested. Both compounds slowed the deactivation of tail currents and lead to the appearance of slowly activating and slowly deactivating current components. However, SDZ-202 791 had larger effects on deactivation and CGP 48506 had larger effect on the rate of Ca 2+ current activation. The effect of SDZ-202 791 was fully additive to that of CGP 48506 even after maximum concentrations of CGP. This observation suggests that the two Ca 2+ channel agonists may act at two different sites on the L-type Ca 2+ channel. We suggest that CGP 48506 would be a potential cardiotonic agent without the deleterious proarrhythmic effects attributable to the dihydropyridine agonists.
Can J Physiol Pharmacol, 1996
Xenopus laevis oocytes can be selected to express relatively high levels of endogenous Ca current... more Xenopus laevis oocytes can be selected to express relatively high levels of endogenous Ca currents. These currents are facilitated by prepulses. Facilitated endogenous Ca currents are unaffected by okadaic acid, RpcAMPS or the dihydropyridine (DHP) antagonist (+) PN 200-110. The endogenous currents and facilitation of endogenous currents by depolarizing prepulses are fully blocked by 1 mM Cd2+. In contrast, oocytes injected with mRNA encoding for the rabbit cardiac alpha 1-subunit express prepulse-facilitated Ca channel currents that are highly enhanced by the phosphoprotein phosphatase inhibitor okadaic acid (3-fold) and blocked by RpcAMPS and the DHP antagonist (+) PN 200-110. While okadaic acid selectively stimulates prepulse facilitation of cardiac alpha 1-subunit Ca currents, the DHP agonist (+) SDZ 202-791 largely increases (5-fold) both the control (before prepulse) and facilitated currents (after prepulse). (+) SDZ 202-791 did not prevent the effect of RpcAMPS or okadaic acid on facilitation of cardiac alpha 1-subunit, suggesting that DHP stimulation is independent of phosphorylation leading to channel facilitation. The enhancement of prepulse facilitation of cardiac alpha 1L-subunit Ca channel current by okadaic acid can be accounted for by a speeding up in the rates of onset during the prepulse. Inhibition of phosphoprotein phosphatases by okadaic acid has only modest effects on the rates of recovery of cardiac alpha 1-subunit Ca channel current from facilitation in the time immediately following the prepulse.
The American journal of physiology
Modulation of Ca2+ channels during repetitive activity in excitable cells can have an important r... more Modulation of Ca2+ channels during repetitive activity in excitable cells can have an important role in altering cellular function. In mammalian parasympathetic and dorsal root ganglion neurons, L-type Ca2+ channels are potentiated by single depolarizing prepulses or trains of short high-frequency depolarizing pulses. This type of potentiation takes place regardless of whether Ca2+ or Ba2+ is the charge carrier and requires phosphorylation by a adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase. The magnitude of facilitation was correlated with frequency of conditioning trains, was enhanced by 8-bromoadenosine 3',5'-cyclic monophosphate or the Sp diastereomer of adenosine 3',5'-cyclic monophosphothioate (cAMPS), and reduced by Rp-cAMPS or a peptide inhibitor of cAMP-dependent protein kinase. The N-type Ca2+ channels exhibited the opposite response to these agents. We propose that the potentiation of L-type Ca2+ channel currents in neurons is due to state-dependent phosphorylation by cAMP-dependent protein kinase (Sculptoreanu, A., T. Scheuer, and W. A. Catterall. Nature Lond. 364: 240-243, 1993; Sculptoreanu, A., E. Rotman, M. Takahashi, T. Scheuer, and W. A. Catterall. Proc. Natl. Acad. Sci. USA 90: 10135-10139, 1993.). Thus state-dependent phosphorylation in neurons may be a mechanism for the regulation of various functions including transmitter release.
The American journal of physiology
ABSTRACT
Medical Science Symposia Series, 1995
... Karen S. De Jongh*, Eric I. Rotman, Adrian Sculptoreanu, Brian J. Murphy, Todd Scheuer, and W... more ... Karen S. De Jongh*, Eric I. Rotman, Adrian Sculptoreanu, Brian J. Murphy, Todd Scheuer, and William A. Catterall Department of Pharmacology, SJ-30 ... 6. Rotman EI, De Jongh KS, Florio V, Lai Y, Catterall W A. Specific phosphorylation of a COOH-terminal site on the full-length ...
Neurochemical research, 2001
We used patch clamp recording techniques to determine if muscarinic signaling mechanisms are pres... more We used patch clamp recording techniques to determine if muscarinic signaling mechanisms are present in dissociated autonomic neurons obtained from the major pelvic ganglion, which provides the cholinergic innervation of the urinary bladder and other pelvic organs. The M1 specific agonist, McN-A-343 (2-30 microM) enhanced Ca2+ currents in approximately 37% of neurons (by 50-80%). This enhancement was reduced by atropine (5-10 microM) or a PKC inhibitor (bisindolylmaleimide, 50-200 nM). In responsive neurons Ca2+ currents were also enhanced by the phorbol ester, phorbol-12,13-dibutyrate (50-300 nM) and the dihydropyridine agonist Bay K 8644 (5 microM) and had kinetics of activation and inactivation as expected for L-type Ca2+ channels. We conclude that in a subpopulation of MPG neurons, M1-mediated activation of PKC phosphorylates and enhances L-type Ca2+ channel activities. This muscarinic facilitatory mechanism in MPG neurons may be the same as the M1-mediated facilitation of trans...
The Journal of pharmacology and experimental therapeutics, 1998
The myocardial effect of alpha-1A adrenoceptor (alpha-1 AR) agonists in neonatal rats are mediate... more The myocardial effect of alpha-1A adrenoceptor (alpha-1 AR) agonists in neonatal rats are mediated by alpha-1A AR and not by alpha-1B AR, although both receptor subtypes are equally expressed; the functions of alpha-1B AR are not known. Here, we report that alpha-1 B ARs inhibit the activities of alpha-1A ARs in neonatal rat myocardium so that the inactivation of alpha-1 B ARs by chloroethylclonidine (CEC) potentiated the effects of nonselective alpha-1 AR agonist phenylephrine (PE) on myocardial protein synthesis and early gene (c-fos and c-jun) expression. CEC did not modify the hypertrophic effect of angiotensin II. The potentiation of the effects of PE by CEC was associated with a translocation of Ca(++)-dependent protein kinase C (PKC)alpha, which did not occur in the absence of CEC. Alpha-1A AR-selective agonist A61603 was approximately 1000-fold more potent than PE as a positive inotropic agent; it caused the translocation of PKC alpha, which was not affected by CEC. 5-Methyl...
Molecular and cellular biochemistry, 1997
In the present study, the whole-cell voltage clamp technique was used in order to record the T- a... more In the present study, the whole-cell voltage clamp technique was used in order to record the T- and L-type Ca2+ currents in single heart cells of newborn and young normal and hereditary cardiomyopathic hamsters. Our results showed that the I/V relationship curve as well as the kinetics of the L-type Ca2+ currents (ICa(L)) in both normal and cardiomyopathic heart cells were the same. However, the proportion of myocytes from normal heart hamster that showed L-type ICa was less than that of heart cells from cardiomyopathic hamster. The I/V relationship curve of the T-type ICa (ICa(T)) was the same in myocytes of both normal and cardiomyopathic hamsters. The main differences between ICa(T) of cardiomyopathic and normal hamster are a larger window current and the proportion of ventricular myocytes that showed this type of current in cardiomyopathic hamster. The high density of ICa(T) as well as the large window current and proportion of myocytes showing ICa(T) may explain in part Ca2+ ov...
Developments in Cardiovascular Medicine, 1994
DMD is one of the most common and severest form of SM dystrophy that affects humans (for review s... more DMD is one of the most common and severest form of SM dystrophy that affects humans (for review see 16, 17). The basic problem in DMD is the lack of knowledge of the causes of the disease and the exact nature of events during initiation and progression of the segmental necrosis as a result, patients with DMD still face a
Molecular Therapy, 2006
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Muscle & Nerve, 1990
Muscle myotube cultures were obtained from normal and Duchenne muscular dystrophy (DMD) biopsies ... more Muscle myotube cultures were obtained from normal and Duchenne muscular dystrophy (DMD) biopsies by using an explant technique. The currentvoltage (IN) curve of the whole sodium (Na+) current ( I , , ) in normal myotubes was similar to that obtained from DMD myotubes. However, the inactivation curve of the whole I , , was different in normal myotubes when compared to that obtained from DMD myotubes. Addition of lOP4M tetrodotoxin (TTX, a fast I , , blocker) decreased the whole I , , in both preparations. The inorganic calcium (Ca") blocker manganese (Mn2+) completely blocked the remaining TTX-resistant I , , of normal myotubes and decreased this current in DMD myotubes leaving behind a TTX-and Mnz+insensitive lNa that was insensitive to the Ca2+ blocker desmetoxyverapamil ((-)D888). The slow inward barium current (lea) of both normal and DMD myotubes was blocked by Mn2+ and (-)D888. However the kinetics of the slow channel in normal myotubes was different from that of DMD myotubes. This study demonstrates the presence of a TTXand Mn2+-insensitive iNa in DMD myotubes. This channel may contribute to the increase of intracellular Na+ ([NaIi) in DMD and allow Ca2' to enter the cells through the Na+-Ca2+ exchanger, thus contributing to calcium loadin Key words: Duchenne muscular dystrophy TTX-and Mn"4nsensitive current sodium current calcium current calcium blocker MUSCLE 81 NERVE 13:939-948 1990
Proceedings of the National Academy of Sciences, 1993
Barium currents mediated by the alpha 1 subunit of the cardiac L-type Ca channel expressed in Chi... more Barium currents mediated by the alpha 1 subunit of the cardiac L-type Ca channel expressed in Chinese hamster ovary (CHO) cells were increased up to 10-fold during dialysis of the cell with the catalytic subunit of cAMP-dependent protein kinase. After partial activation by exogenous kinase, the activity of the alpha 1 subunit was also reversibly potentiated up to 3.5-fold by prepulses to voltages in the range of 0 to +150 mV. Potentiation at +48 mV developed with a biphasic time course with time constants of 131 ms and 8 s. Reversal at -60 mV was biphasic with half-times of 12 ms and 100 ms and was blocked in the presence of the phosphatase inhibitor okadaic acid. Both the increase in calcium-channel activity during dialysis with kinase and the voltage-dependent potentiation were accompanied by shifts in the voltage dependence of activation to more negative membrane potentials. The increases in Ba current due to protein phosphorylation and to the dihydropyridine Ca channel agonist Bay K8644 were approximately additive. The results show that the alpha 1 subunit of the cardiac L-type Ca channel is sufficient for substantial modulation of Ca-channel activity by cAMP-dependent protein kinase and for potentiation by state-dependent protein phosphorylation. Voltage-dependent potentiation of the activity of the alpha 1 subunit may contribute to the increase in contractile force in response to increased rate of stimulation, the positive staircase effect in heart muscle.
Pflügers Archiv European Journal of Physiology, 1988
The whole-cell voltage clamp technique was used in order to study the effects of Angiotensin II (... more The whole-cell voltage clamp technique was used in order to study the effects of Angiotensin II (Ang II) on the slow inward current and the K+outward current in single aortic cells of the rabbit-a~gi~tensin II (IO-~M) increased the slow inward current, and the addition of an antagonist of Ang II, ([Leu 8] Ang II, Io-SM) rapidly reversed the effect of Ang II on IBa. Angiotensin II (5 x IO-8M) greatly decreased K § current and the Ang II antagonist reversed this effect.
Peptides, 2005
The effect of angiotensin II (Ang II) on the T-and L-type calcium currents (I Ca ) in single vent... more The effect of angiotensin II (Ang II) on the T-and L-type calcium currents (I Ca ) in single ventricular heart cells of 18-week-old fetal human and 10-day-old chick embryos was studied using the whole-cell voltage clamp technique. Our results showed that in both, human and chick cardiomyocytes, Ang II (10 −7 M) increased the T-type calcium current and decreased the L-type I Ca . The effect of Ang II on both types of currents was blocked by the AT 1 peptidic antagonist, [Sar 1 , Ala 8 ] Ang II (2 × 10 −7 M). Protein kinase C activator, phorbol 12,13-dibutyrate, mimicked the effect of Ang II on the T-and L-type calcium currents. These results demonstrate that in fetal human and chick embryo cardiomyocytes Ang II affects the T-and L-type Ca 2+ currents differently, and this effect seems to be mediated by the PKC pathway.
Nature Methods, 2007
Pathological alterations of ion channel activity result from changes in modulatory mechanisms gov... more Pathological alterations of ion channel activity result from changes in modulatory mechanisms governing receptor biology. Here we describe a conditional herpes simplex virus (HSV) replication-based strategy to discover channel modulators whereby inhibition of agonist-induced channel activation by a vector-expressed modulatory gene product prevents ion flux, osmotic shock and cell death. Inhibition of channel activity, in this case, the rat vanilloid (Trpv1) or the glycine receptor (GlyRα1), can allow selection of escape vector plaques containing the 'captured' modulatory gene for subsequent identification and functional analysis. We validated this prediction using mixed infections of a wild-type Trpv1 expression vector vTTHR and a nonfunctional 'poreless' Trpv1 subunit-expressing vector, vHP, wherein vHP was highly selected from a large background of vTTHR viruses in the presence of the Trpv1 agonist, capsaicin. The approach should be useful for probing large libraries of vector-expressed cDNAs for the presence of ion channel modulators.
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Papers by Adrian Sculptoreanu