Nitric oxide and prostacyclin play a role in the regulation of microvascular protein and hydraulic permeability in cat skeletal muscle.
OBJECTIVE
To evaluate a possible role of nitric oxide (NO) and prostacyclin in the regulation of basal microvascular protein and hydraulic permeability.


METHODS
The study was performed on the autoperfused cat calf muscle. Changes in the osmotic reflection coefficient for albumin, calculated from the extended Starling equation, were used as a measure of altered protein permeability, whereas changes in capillary filtration coefficient (CFC) were used as a measure of altered hydraulic permeability.


RESULTS
Inhibition of the endogenous NO production with L-nitro-arginine methyl ester given intra-arterially to the muscle decreased the reflection coefficient to 70% of the control (p < 0.05) and increased the CFC by 17% (p < 0.05). The addition of a simultaneous intra-arterial infusion of the NO precursor L-arginine restored both the reflection coefficient and the CFC back to control level. Blockade of the endogenous prostacyclin production with tranylcypromine given intra-arterially decreased the reflection coefficient to 72% of the control (p < 0.05) and increased the CFC by 24% (p < 0.05), and they were both restored to control levels by a simultaneous intravenous infusion of a nonvasodilating dose of prostacyclin (1.0 ng/kg per minute).


CONCLUSIONS
The results support the view that endogenous NO and prostacyclin decrease both protein and hydraulic permeability. Assuming a dynamic endogenous release of these substances, they may act as bidirectional regulators of protein and hydraulic permeability.
Persson
Johan
J
Department of Physiology, University of Lund and University Hospital of Lund, Lund, Sweden.
Ekelund
Ulf
U
Grände
Per-Olof
PO
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002199:Capillary Permeability; D002415:Cats; D011464:Epoprostenol / Q000502:physiology*; D006614:Hindlimb; D066298:In Vitro Techniques; D008833:Microcirculation / Q000166:cytology / Q000378:metabolism; D018482:Muscle, Skeletal / Q000098:blood supply*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D011506:Proteins / Q000378:metabolism*; D014655:Vascular Resistance
D011506:Proteins; D009569:Nitric Oxide; D001120:Arginine; D011464:Epoprostenol; D019331:NG-Nitroarginine Methyl Ester