Essential role of L‐arginine uptake and protein tyrosine kinase activity for NO‐dependent vasorelaxation induced by stretch, isometric tension and cyclic AMP in rat pulmonary arteries

Abstract

1 The NO-dependent component of cyclic AMP-induced vasorelaxation in rat pulmonary arteries is critically dependent on extracellular L-arginine but independent of endothelial cell intracellular [Ca 2+ ]. We examined whether L-arginine uptake was also essential for NO production induced by passive stretch or isometric tension, processes also reported to be Ca 2+ -independent. 2 The passive length-tension curve was depressed by physiological concentrations of L-arginine (400 mM; P50.05). Inhibition of the y + transporter with 10 mM L-lysine, NO synthase with L-NAME (100 mM), or protein tyrosine kinase with erbstatin A (30 mM) caused identical upward shifts (P50.001), alone or in combination. Tyrphostin 23 was similar to erbstatin A, whilst the inactive analogue tyrphostin A1 and genistein were without eect. 3 L-arginine (400 mM) shifted the PGF 2a concentration-response curve under isometric conditions to the right (P50.05), whereas L-NAME or L-lysine caused a leftward shift (P50.001). Tyrphostin 23 (30 mM) more than reversed the L-arginine-induced suppression of PGF 2a -induced tension; subsequent addition of L-NAME had no eect. The L-lysine-sensitive component of CPT cyclic AMP-induced vasorelaxation was abolished by erbstatin A. 4 ACh-induced vasorelaxation was *80% inhibited by L-NAME, but was not aected by L-lysine or 400 mM L-arginine. Erbstatin A reduced the vasorelaxation by only *25%. 5 We conclude that activation of NO production by stretch, isometric tension, or cyclic AMP in rat pulmonary arteries is critically dependent on the presence and uptake of physiological concentrations of extracellular L-arginine, and protein tyrosine kinase activity. This directly contrasts with ACh-induced vasorelaxation, which was independent of extracellular L-arginine, and relatively unaected by tyrosine kinase inhibition.

Modulation of PGF2α- and hypoxia-induced contraction of rat intrapulmonary artery by p38 MAPK inhibition: a nitric oxide-dependent mechanism

“…It was not surprising that stimulation with PGF 2␣ alone resulted in increased production since the stimulation of NO production by contractile agonists is well documented (e.g., see Ref. 19) and indeed specifically with PGF 2␣ in IPA (16). However, the combination of SB-203580 and PGF 2␣ caused a rise in cGMP similar to that induced by PGF 2␣ alone, suggesting that under the conditions used in our experiments SB-203580 was not affecting the release of NO or its ability to stimulate guanylate cyclase.…”

Leptin Effect on Endothelial Nitric Oxide Is Mediated Through Akt–Endothelial Nitric Oxide Synthase Phosphorylation Pathway

“…Taken together, our data suggest that NO production evoked by leptin is realized through an intracellular calcium-independent signaling pathway converging on Akt phosphorylation, which does not involve the activation of PI 3-kinase but instead requires tyrosine phosphorylation that is sensitive to erbstatin A but not genistein. This latter finding, that two diverse tyrosine kinase inhibitors realize different effects, could seem conflicting, but several reports have described a similar lack of effect of genistein on NO production realized by application of other stimuli, suggesting that Akt phosphorylation and the consequent NO release is regulated by one or more tyrosine kinases with differential sensitivity to the inhibitors used (29,30). It is noteworthy to emphasize that the inhibitory effect of erbstatin A cannot be ascribed to a direct interference with eNOS tyrosine phosphorylation, because a preliminary event in the eNOS activation cascade, such as Akt phosphorylation, is also inhibited by erbstatin A.…”

Resting Tension Affects eNOS Activity in a Calcium-Dependent Way in Airways

“…In vessels, it has been demonstrated that L-arginine uptake is involved in NO production caused by mechanical stimuli, but L-arginine is not required for ACh-induced NO production [25, 26] or for the increase in eNOS activity by tyrosine phosphorylation [5–7]. Results from the present study demonstrate that at 2.5 g RT, the extracellular calcium concentration, NOS or tyrosine kinase inhibitors and L-arginine did not alter passive tension.…”