Wg. Mayhan, NITRIC-OXIDE ACCOUNTS FOR HISTAMINE-INDUCED INCREASES IN MACROMOLECULAR EXTRAVASATION, The American journal of physiology, 266(6), 1994, pp. 80002369-80002373
The goal of this study was to determine the role of nitric oxide in hi
stamine-induced increases in macromolecular extravasation in the hamst
er cheek pouch in vivo. We used intravital fluorescent microscopy and
fluorescein isothiocyanate dextran (FITC-dextran; mol wt = 70,000 K) t
o examine extravasation from postcapillary venules in response to hist
amine before and after application of an enzymatic inhibitor of nitric
oxide, NG-monomethyl-L-arginine (L-NMMA; 1.0 CLM) Increases in extrav
asation of macromolecules were quantitated counting the number of venu
lar leaky sites. Histamine (1.0 and 5.0 CLM) increased the number of v
enular leaky sites from zero (basal conditions) to 11 +/- 1 and 21 +/-
2/0.11 cm(2), respectively. Superfusion of L-NMMA (1.0 mu M) and LY-8
3583 (1.0 mu M) significantly decreased histamine-induced formation of
venular leaky sites, whereas L-arginine (100 mu M) potentiated histam
ine-induced formation of venular leaky sites. In contrast, superfusion
of N-G-monomethyl-D-arginine (1.0 mu M) did not inhibit the formation
of venular leaky sites in response to histamine. Thus the findings of
the present study suggest that production of nitric oxide, and subseq
uent activation of guanylate cyclase, plays an important role in macro
molecular efflux in vivo in response to histamine.