TY - JOUR
T1 - Neuronal nitric oxide synthase signaling within cardiac myocytes targets phospholamban
AU - Wang, Honglan
AU - Kohr, Mark J.
AU - Traynham, Christopher J.
AU - Wheeler, Debra G.
AU - Janssen, Paul M.L.
AU - Ziolo, Mark T.
PY - 2008/6
Y1 - 2008/6
N2 - Studies have shown that neuronal nitric oxide synthase (nNOS, NOS1) knockout mice (NOS1-/-) have increased or decreased contractility, but consistently have found a slowed rate of intracellular Ca2+ ([Ca2+]i) decline and relengthening. Contraction and [Ca2+]i decline are determined by many factors, one of which is phospholamban (PLB). The purpose of this study is to determine the involvement of PLB in the NOS1-mediated effects. Force-frequency experiments were performed in trabeculae isolated from NOS1-/- and wild-type (WT) mice. We also simultaneously measured Ca2+ transients (Fluo-4) and cell shortening (edge detection) in myocytes isolated from WT, NOS1 -/-, and PLB-/- mice. NOS1-/- trabeculae had a blunted force-frequency response and prolonged relaxation. We observed similar effects in myocytes with NOS1 knockout or specific NOS1 inhibition with S-methyl-L-thiocitrulline (SMLT) in WT myocytes (i.e., decreased Ca2+ transient and cell shortening amplitudes and prolonged decline of [Ca 2+]i). Alternatively, NOS1 inhibition with SMLT in PLB-/- myocytes had no effect. Acute inhibition of NOS1 with SMLT in WT myocytes also decreased basal PLB serine16 phosphorylation. Furthermore, there was a decreased SR Ca2+ load with NOS1 knockout or inhibition, which is consistent with the negative contractile effects. Perfusion with FeTPPS (peroxynitrite decomposition catalyst) mimicked the effects of NOS1 knockout or inhibition. β-Adrenergic stimulation restored the slowed [Ca 2+]i decline in NOS1-/- myocytes, but a blunted contraction remained, suggesting additional protein target(s). In summary, NOS1 inhibition or knockout leads to decreased contraction and slowed [Ca 2+]i decline, and this effect is absent in PLB -/- myocytes. Thus NOS1 signaling modulates PLB serine16 phosphorylation, in part, via peroxynitrite.
AB - Studies have shown that neuronal nitric oxide synthase (nNOS, NOS1) knockout mice (NOS1-/-) have increased or decreased contractility, but consistently have found a slowed rate of intracellular Ca2+ ([Ca2+]i) decline and relengthening. Contraction and [Ca2+]i decline are determined by many factors, one of which is phospholamban (PLB). The purpose of this study is to determine the involvement of PLB in the NOS1-mediated effects. Force-frequency experiments were performed in trabeculae isolated from NOS1-/- and wild-type (WT) mice. We also simultaneously measured Ca2+ transients (Fluo-4) and cell shortening (edge detection) in myocytes isolated from WT, NOS1 -/-, and PLB-/- mice. NOS1-/- trabeculae had a blunted force-frequency response and prolonged relaxation. We observed similar effects in myocytes with NOS1 knockout or specific NOS1 inhibition with S-methyl-L-thiocitrulline (SMLT) in WT myocytes (i.e., decreased Ca2+ transient and cell shortening amplitudes and prolonged decline of [Ca 2+]i). Alternatively, NOS1 inhibition with SMLT in PLB-/- myocytes had no effect. Acute inhibition of NOS1 with SMLT in WT myocytes also decreased basal PLB serine16 phosphorylation. Furthermore, there was a decreased SR Ca2+ load with NOS1 knockout or inhibition, which is consistent with the negative contractile effects. Perfusion with FeTPPS (peroxynitrite decomposition catalyst) mimicked the effects of NOS1 knockout or inhibition. β-Adrenergic stimulation restored the slowed [Ca 2+]i decline in NOS1-/- myocytes, but a blunted contraction remained, suggesting additional protein target(s). In summary, NOS1 inhibition or knockout leads to decreased contraction and slowed [Ca 2+]i decline, and this effect is absent in PLB -/- myocytes. Thus NOS1 signaling modulates PLB serine16 phosphorylation, in part, via peroxynitrite.
KW - Force-frequency response
KW - NOS1
KW - Peroxynitrite
UR - http://www.scopus.com/inward/record.url?scp=47249116239&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=47249116239&partnerID=8YFLogxK
U2 - 10.1152/ajpcell.00367.2007
DO - 10.1152/ajpcell.00367.2007
M3 - Article
C2 - 18400986
AN - SCOPUS:47249116239
SN - 0363-6143
VL - 294
SP - C1566-C1575
JO - American Journal of Physiology - Cell Physiology
JF - American Journal of Physiology - Cell Physiology
IS - 6
ER -