Opposing effects of L-NAME on capillary filtration rate in the presence or absence of neutrophils.
Fluid filtration rate (JV/S) from rat mesenteric capillaries was measured using a modified Landis technique before and after superfusion with 100 microM NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor. Three groups were studied: 1) control rats, 2) rats injected with antineutrophil serum (ANS), and 3) rats injected with a monoclonal antibody (CL26) against the leukocyte adhesion molecule CD18. The relative increase in JV/S (L-NAME/ baseline) in control rats averaged 1.66 +/- 0.32 (n = 11), which was significantly higher (P < 0.05) than in ANS (0.51 +/- 0.12; n = 5)- and CL26 (0.45 +/- 0.16; n = 6)-injected rats exposed to L-NAME. The L-NAME-induced changes in JV/S in each group were due to altered permeability rather than altered pressure gradients, as determined by measurements of arteriolar hydrostatic pressure (using a servo-null apparatus) and estimates of intravascular oncotic pressure (using plasma protein concentration). These findings indicate that nitric oxide synthase inhibition increases the permeability of mesenteric capillaries to water, a response that is dependent on neutrophil adhesion.
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Department of Molecular and Cellular Physiology, Louisiana State University Medical Center, Shreveport 71130-3932, USA.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D018821:CD18 Antigens / Q000276:immunology / Q000502:physiology; D002196:Capillaries / Q000187:drug effects / Q000502:physiology*; D005374:Filtration; D007106:Immune Sera / Q000494:pharmacology; D008297:Male; D018715:Microscopy, Video; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009504:Neutrophils / Q000276:immunology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013152:Splanchnic Circulation / Q000187:drug effects / Q000502:physiology*
D000911:Antibodies, Monoclonal; D018821:CD18 Antigens; D007106:Immune Sera; D019331:NG-Nitroarginine Methyl Ester