Xf. Figueroa et al., In vivo assessment of microvascular nitric oxide production and its relation with blood flow, AM J P-HEAR, 280(3), 2001, pp. H1222-H1231
Citations number
29
Categorie Soggetti
Cardiovascular & Hematology Research
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
To assess the hypothesis that microvascular nitric oxide (NO) is critical t
o maintain blood flow and solute exchange, we quantified NO production in t
he hamster cheek pouch in vivo, correlating it with vascular dynamics. Hams
ters (100-120 g) were anesthetized and prepared for measurement of microves
sel diameters by intravital microscopy, of plasma flow by isotopic sodium c
learance, and of NO production by chemiluminescence. Analysis of endothelia
l NO synthase (eNOS) location by immunocytochemistry and subcellular fracti
onation revealed that eNOS was present in arterioles and venules and was 67
+/- 7% membrane bound. Basal NO release was 60.1 +/- 5.1 pM/min (n = 35),
and plasma flow was 2.95 +/- 0.27 mul/min (n = 29). Local NO synthase inhib
ition with 30 muM N-omega-nitro-L-arginine reduced NO production to 8.6 +/-
2.6 pmol/min (-83 +/- 5%, n = 9) and plasma flow to 1.95 +/- 0.15 mul/min
(-28 +/- 12%, n = 17) within 30-45 min, in parallel with constriction of ar
terioles (9-14%) and venules (19-25%). The effects of N-omega-nitro-L-argin
ine (10-30 muM) were proportional to basal microvascular conductance (r = 0
.7, P< 0.05) and fully prevented by 1 mM L-arginine. We conclude that in th
is tissue, NO production contributes to 35-50% of resting microvascular con
ductance and plasma-tissue exchange.