Modulation of in vivo cardiac function by myocyte-specific nitric oxide synthase-3.
Nitric oxide (NO) functions principally as a diffusible paracrine effector. The exception is in cardiomyocytes where both NO synthases (NOS) and target proteins coexist, allowing NO to work in an autocrine/intracrine fashion. However, the most abundant myocyte isoform (NOS3) is far more expressed in vascular endothelium; thus, the in vivo contribution of myocyte-NOS3 remains less clear. The present study tested this role by transfecting whole hearts of NOS3-null (NOS3(-/-)) mice with adenovirus-expressing NOS3 coupled to a alpha-MHC promoter (AdV(NOS3)), comparing results to hearts transfected with marker-gene beta-galactosidase (AdVbeta(gal)). Total myocardial NOS3 protein and activity were restored to near wild-type (WT) levels in NOS3(-/-)+AdV(NOS3) hearts, and NOS3 relocalized normally with caveolin-3. Ejection function by pressure-volume analysis was enhanced in NOS3(-/-)+AdVbeta(gal) over WT or NOS3(-/-)+AdV(NOS3). More prominently, isoproterenol (ISO)-stimulated systolic and diastolic function in WT was amplified in NOS3(-/-)+AdVbeta(gal), whereas NOS3(-/-)+AdV(NOS3) returned the response to control. ISO-activated systolic function was inhibited 85% by concomitant muscarinic stimulation (carbachol) in NOS3(-/-)+AdV(NOS3) but not NOS3(-/-)+AdVbeta(gal) hearts. Lastly, NOS3(-/-)+AdVbeta(gal) mice displayed enhanced inotropy and lusitropy over WT at slower heart rates but a blunted rate augmentation versus controls. A more positive rate response was restored in NOS3(-/-)+AdV(NOS3) (P<0.001). Thus, myocyte autocrine/intracrine NOS3 regulation in vivo can underlie key roles in beta-adrenergic, muscarinic, and frequency-dependent cardiac regulation.
Champion
Hunter C
HC
Division of Cardiology, Department of Medicine, Johns Hopkins Hospital, Baltimore, MD 21287, USA.
Georgakopoulos
Dimitrios
D
Takimoto
Eiki
E
Isoda
Takayoshi
T
Wang
Yibin
Y
Kass
David A
DA
D000256:Adenoviridae / Q000235:genetics; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D019898:Autocrine Communication; D002217:Carbachol / Q000494:pharmacology; D003331:Coronary Vessels / Q000201:enzymology; D004730:Endothelium, Vascular / Q000201:enzymology; D005822:Genetic Vectors / Q000008:administration & dosage; D006339:Heart Rate; D007545:Isoproterenol / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018721:Muscarinic Agonists / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000201:enzymology / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D014161:Transduction, Genetic; D014162:Transfection
D000318:Adrenergic beta-Agonists; D018721:Muscarinic Agonists; D009569:Nitric Oxide; D002217:Carbachol; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D007545:Isoproterenol