Flow modulates the transport of K+ through the walls of single perfused mesenteric venules in anaesthetised rats

摘要

class="enumerated" style="list-style-type:decimal">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 μm s⁻¹.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 Uare both expressed in micrometres per second (μm s⁻¹).The addition of the nitric oxide (NO) synthase inhibitors (20 μmol 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 μmol 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)) × 10⁻⁴ (n= 4). The addition of L-arginine (200 μmol l⁻¹) restored the relation between PK and U where the slope of the relation was increased from 3·9 (± 16·3 IQR) × 10⁻⁴ to 69·2 (± 13·5 IQR) × 10⁻⁴ (n= 7).The addition of the guanylate cyclase inhibitor LY83583 (10 μmol l⁻¹) abolished the positive correlation between PK and U (n= 6).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.