Increased nitric oxide release and expression of endothelial and inducible nitric oxide synthases in mildly changed porcine mitral valve leaflets.
OBJECTIVE
Little is known of the local role of nitric oxide (NO) in heart valves in relation to heart valve diseases. The study aim was to examine NO release and the expression of both endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in relation to early local changes in porcine mitral valves.


METHODS
A histological evaluation of mitral valve leaflets from slaughter pigs and sows was made, and the expression of eNOS and iNOS protein measured using immunohistochemistry. Furthermore, mRNA levels of eNOS and iNOS were measured using real-time RT-PCR. A calibrated NO-specific electrode was used to measure local NO release in specific regions of the anterior mitral leaflet from slaughter pigs and sows interchordally at the tip of the leaflet (region A), at the chordal insertion (region B), and at the center of the leaflet (region C).


RESULTS
Leaflets from sows had an increased accumulation of mucopolysaccharides (MPS) compared to those from slaughter pigs. Furthermore, mRNA levels of eNOS and iNOS were significantly increased in region C due to very high levels of expression in some sow leaflets. NO release in the sow mitral valve leaflet was increased in regions B and C compared to that in region A.


CONCLUSIONS
The relative distribution of NO release is increased in regions of porcine mitral valve leaflets with deposition of MPS and defraction of the valve structure, which may reflect changes in both eNOS and iNOS expression.
Moesgaard
Sophia G
SG
Department of Basic Animal and Veterinary Sciences, The Royal Veterinary and Agricultural University, 7 Groennegaardsvej, 1870 Frederiksberg, Denmark. som@kvl.dk
Olsen
Lisbeth H
LH
Viuff
Birgitte M
BM
Baandrup
Ulrik
U
Pedersen
Lotte G
LG
Thomsen
Preben D
PD
Pedersen
Henrik D
HD
Harrison
Adrian P
AP
D000818:Animals; D005260:Female; D006025:Glycosaminoglycans / Q000032:analysis; D008297:Male; D008943:Mitral Valve / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000096:biosynthesis*; D013552:Swine
D006025:Glycosaminoglycans; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III