Flow modulates the transport of K+ through the walls of single perfused mesenteric venules in anaesthetised rats.
1. We have investigated the effects of varying flow velocity (U) upon permeability to potassium ions (PK) of single perfused mesenteric venules in anaesthetised rats. PK was estimated using a development of the single bolus microperfusion technique at chosen flow velocities in the range of 300 to 6000 microm s-1. 2. In an initial study on 12 vessels, there was a strong positive correlation between PK and U. This was described by the relation: PK = 0.0053U + 8.86, where PK and U are both expressed in micrometres per second (microm s-1). 3. The addition of the nitric oxide (NO) synthase inhibitors (20 micromol l-1) N G-monomethyl-L-arginine (L-NMMA) and N G-nitro L-arginine (L-NNA) to the superfusate abolished the positive correlation between PK and U. The addition of D-NNA (20 micromol l-1) did not change the relation between PK and U where the median value for the slope of the relation was 57.7 (+/- 58.7 interquartile (IQR)) x 10-4 (n = 4). The addition of L-arginine (200 micromol l-1) restored the relation between PK and U where the slope of the relation was increased from 3.9 (+/- 16.3 IQR) x 10-4 to 69.2 (+/- 13.5 IQR) x 10-4 (n = 7). 4. The addition of the guanylate cyclase inhibitor LY83583 (10 micromol l-1) abolished the positive correlation between PK and U (n = 6). 5. Our data suggest that the flow modulates the potassium permeability through the walls of single perfused rat mesenteric venules via a NO-cGMP-dependent process.
Kajimura
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Section of Cellular & Integrative Biology, Division of Biomedical Sciences, Imperial College School of Medicine, South Kensington, London, UK.
Michel
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D000465:Algorithms; D000634:Aminoquinolines / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002138:Calibration; D004058:Diffusion; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008297:Male; D008642:Mesenteric Veins / Q000187:drug effects / Q000378:metabolism*; D008839:Microelectrodes; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052250:Nitric Oxide Synthase Type III; D019335:Nitroarginine / Q000494:pharmacology; D010477:Perfusion; D010539:Permeability; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000634:Aminoquinolines; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D019335:Nitroarginine; C041715:6-anilino-5,8-quinolinedione; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D006162:Guanylate Cyclase; D011188:Potassium