1 The influence of the nitric oxide (NO) biosynthesis inhibitor N0-nitro-L-arginine methyl ester (L-NAME) on the gastric relaxation induced by peripheral vagal stimulation was investigated in the anaesthetized rat.2 Peripheral vagal stimulation (10 Hz, 10 V, 1 ms for 20 s) induced a reproducible biphasic response: a short-lasting increase followed by a more pronounced decrease in intragastric pressure. This response also occurred in reserpinized animals (5mg kg-, i.p., 24 h before the experiment) while atropine (1 mg kg1, i.v.) abolished the initial increase in intragastric pressure. 3 L-NAME (1-30mg kg-',i.v.) induced an increase in arterial blood pressure. L-NAME (1 mg kg-i.v.) had no influence on the vagally induced gastric response while L-NAME (10 and 30mgkg-' i.v.) significantly changed it: the initial increase in intragastric pressure was enhanced while the decrease in intragastric pressure was reduced or abolished. N0-nitro-L-arginine (L-NNA, l0 mg kg-%, i.v.) had the same effect.4 An i.v. infusion of phenylephrine (10pgkg-lmin-1) inducing a pressor response similar to that produced by L-NAME (30mgkg-1, i.v.) did not influence the vagal gastric response. Infusion of L-arginine (300mgkg-' bolus, then lOOmgkg-lh-') starting 30min beforehand, reduced the pressor effect and prevented the influence of L-NAME (lOmgkg-, i.v.) on the vagal gastric response. After injection of both atropine (lmgkg-', i.v.) and L-NAME (30mgkg-', i.v.), the vagally induced decrease in intragastric pressure was similar to that obtained under control conditions. 5 These results are consistent with NO being released and inducing gastric relaxation during peripheral vagal stimulation. In addition to NO, another inhibitory non-adrenergic non-cholinergic neurotransmitter is released.

Background: Vitamin deficiency is common in chronic kidney disease (CKD). Data on B₆ supply and possible relationships to cardiovascular events (CVE) in CKD are rare. Pyridoxamine exerts inhibitory effects on the formation of advanced glycation endproducts (AGE) implicated in the pathogenesis of CKD and atherosclerosis. Methods: In 48 CKD patients at stage 2–4, 72 hemodialysis patients (HD), 38 renal transplant recipients (RTR) and 141 healthy controls (mean age 58 ± 13, 61 ± 12, 50 ± 12 and 54 ± 16 years, respectively), plasma and red blood cell (RBC) concentrations of pyridoxal-5′-phosphate (PLP), pyridoxal (PL), 4-pyridoxic acid (PA), pyridoxamine-5′-phosphate (PMP) and of the AGE pentosidine were measured by high-performance liquid chromatography, N^Ε-(carboxymethyl)lysine and imidazolone by an ELISA, and total homocysteine and cystathionine by gas chromatography-mass spectrometry. Results: Despite routine low-dose vitamin supplementation in HD, plasma PLP was decreased in HD (79 ± 69 nmol/l) compared with CKD stage 2–4 patients (497 ± 944 nmol/l), RTR (416 ± 604 nmol/l) and controls (159 ± 230 nmol/l; p < 0.001). Plasma PA was significantly increased in HD (11,667 ± 17,871 nmol/l) in comparison with CKD stage 2–4 (435 ± 441 nmol/l), RTR (583 ± 668 nmol/l) and controls (46 ± 49 nmol/l; p < 0.001). B₆ forms were significantly affected by renal function (R = 0.792, p < 0.001 for CKD stage 2–4). There was no relation of vitamers with a history of CVE. Relationships between B₆ forms and AGE (RBC-PMP with pentosidine in CKD stage 2–4: R = –0.351, p < 0.05) were found. Conclusion: HD patients showed a deficiency in PLP in plasma but not in RBC. Prospective trials are needed to elucidate the potential role of elevated PA on cardiovascular and renal outcome in CKD. Vitamin B₆ supplementation might be successful in preventing AGE-related pathologies.