Involvement of P2Y receptors in pyridoxal‐5′‐phosphate‐induced cardiac preconditioning

Abstract

Using an isolated non‐working rat heart model, this study investigated the mechanisms of pharmacological pre‐conditioning (PC) induced by P2Y receptor stimulation with pyridoxal‐5′‐phosphate (PLP). After 6‐hydroxydopamine pretreatment and a 15‐min stabilization period, isolated rat hearts were perfused for 25 min then subjected to 40 min of global ischemia and 30 min of reperfusion (I/R); exposed for 15 min to 0.05 μm PLP bracketed for 25 min with broad‐spectrum P2 antagonists (suramin or PPADS) or with more specific P2Y antagonists (AMPαS or MRS2578), 1 μm each, followed by a 5‐min PLP‐free perfusion before I/R; treated during 25 min with either glybenclamide (GLY, 1 μm), 5‐hydroxydecanoic acid (5‐HD, 100 μm), U73122 (0.5 μm), H89 (1 μm), or KN93 (1 μm), with an infusion starting 5 min before PLP. The main endpoints were the rate–pressure product (RPP), creatine kinase (CK) release and area necrosis. Recovery of RPP, measured 5 min after reperfusion, was rapidly improved by PLP, blocked by the P2 antagonists, and decreased with the different inhibitors. Fifteen minutes after the end of ischemia, CK release reached maximal values in all groups. PLP provided significant protection, whereas the P2 antagonists, 5‐HD, a mitochondrial selective KATP antagonist and GLY a non‐selective KATP channel blocker, suppressed the protective effect on myocardial injury. The suppression of the cardioprotective effects of PLP by AMPαS, the PKA inhibitor (H89), and phospholipase C blocker (U73122) is in agreement with the P2Y11 receptor as a receptor for PLP‐induced PC. The suppression of the cardioprotective effects of PLP by MRS2578 and U73122 is in agreement with the P2Y6 receptor as a receptor for PLP‐induced PC. Pre‐ischemic exposure to nanomolar concentrations of PLP is protective against I/R. P2Y11 and P2Y6 represents the most likely candidate receptors for PLP‐induced cardiac PC.

Exaggerated exercise pressor reflex in adults with moderately elevated systolic blood pressure: role of purinergic receptors

“…However, the ATP-induced increases in [Ca 2ϩ ] i were almost completely abolished in cells incubated in Px, indicating that Px is a viable P2 receptor antagonist in murine neuronal cells. This finding is consistent with similar studies in both neuronal cells and in isolated cardiomyocytes (29,43,60), but to our knowledge, this novel finding is the first demonstration in isolated DRG neurons, which are of particular relevance to the EPR.…”

“…Nonetheless, localized IV infusion of Px into the forearm increased systemic plasma PLP levels ϳ2-fold (see RESULTS), consistent with the increases noted in the available human literature (9). In rats, perfusion of isolated hearts with 0.05 M PLP (i.e., 50 nM) effectively blocks P2 receptors (43). After Px infusion in the current study, plasma PLP was ϳ200 nM, which is sufficient to antagonize P2 receptors.…”

“…Px, the chemical precursor of PLP, is a nonselective P2 receptor antagonist (43,51,60) and can be safely administered to humans (24,55). Venous samples were collected to measure plasma PLP, lactate (Accutrend Lactate; Mannheim, Germany), serum potassium (EasyElectrolyte Analyzer; Medica, Bedford, MA), and pH (Accumet Basic AB15; Cole-Parmer, Vernon Hills, IL).…”

Cardiac purinergic signalling in health and disease

“…Thus, it was proposed that ATP-loaded liposomes could be developed as a treatment for myocardial ischaemia [598]. It has been suggested that P2Y6R and P2Y11R are involved in pyridoxal-5′-phosphate-induced cardiac pre-conditioning in rat hearts [599]. ADP acting on endothelial P2Y1R plays a major role in coronary flow during post-ischaemic hyperaemia [600].…”

Perspectives of purinergic signaling in stem cell differentiation and tissue regeneration

“…Recent research suggests that at least part of the protective effect observed during reperfusion by PLP may be mediated through its inhibitory action on purinergic receptors. The possible receptors expressed in cardiomyocytes and subject to inhibition by PLP are P2Y1, P2Y2, P2Y4, P2Y6, and P2Y11 subtypes [53]. Taking together, the strategy of cell therapy following a heart attack could base on activation of P2Y14 purinergic receptors expressed by bone marrow stem cells which then would induce migration to the site of injury and thus could restore heart tissue before the formation of a scar.…”