**Background**
P2X receptors are a family of ligand-gated ion channels activated by extracellular adenosine triphosphate (ATP), playing critical roles in various physiological processes, including neurotransmission, inflammation, and vascular tone regulation. Dysregulation of these receptors is often associated with pathological conditions such as glomerulonephritis and airway smooth muscle dysfunction. Specifically, the activation of P2X receptors can trigger cellular proliferation and ion exchange imbalances that contribute to tissue damage. Consequently, the development of potent P2X receptor antagonists is essential for understanding these signaling pathways and discovering potential therapeutic interventions. In this context, we will introduce a non-selective P2X receptor antagonist – PPADS tetrasodium.
**Definition**
PPADS tetrasodium is a non-selective P2X receptor antagonist that blocks recombinant P2X1, -2, -3, and -5 receptors with $\text{IC}_{50}$ values ranging from 1 to 2.6 $\mu\text{M}$.
**In Vitro and In Vivo Studies**
According to the PPADS tetrasodium description, this compound also blocks native $\text{P2Y}_2$-like ($\text{IC}_{50} \approx 0.9\text{ mM}$) and recombinant $\text{P2Y}_4$ ($\text{IC}_{50} \approx 15\text{ mM}$) receptors. Regarding PPADS tetrasodium in vitro activity, the compound (1-30 $\mu\text{M}$; 10-50 minutes) inhibits the reverse mode of the $\text{Na}^+/\text{Ca}^{2+}$ exchanger ($\text{NCX}_{\text{REV}}$) in guinea pig airway smooth muscle in a time- and concentration-dependent manner. In human P2X receptors, sensitivity varies by subtype, with the highest potency observed at hP2X1, -2, -3, -5, and -7Rs ($\text{IC}_{50} \approx 1\text{-}3\text{ }\mu\text{M}$) and a lower potency at hP2X4R ($\text{IC}_{50} \approx 30\text{ }\mu\text{M}$).
Furthermore, PPADS tetrasodium In Vivo studies have demonstrated its efficacy in renal models. In male Sprague-Dawley rats (160 to 200 g) with anti-Thy1 induced mesangial proliferative glomerulonephritis, PPADS tetrasodium was administered i.p. every 12 hours for 8 days at doses of 15, 30, and 60 mg/100g body weight (BW). The loading dose was doubled compared to subsequent injections. The results showed that the compound specifically and dose-dependently reduced early (day 3) glomerular mesangial cell (MC) proliferation without altering the proliferation of non-MC. For researchers seeking detailed PPADS tetrasodium technical information, these results highlight its potential in managing proliferative renal diseases. In conclusion, PPADS tetrasodium is a potent non-selective P2X receptor antagonist and $\text{NCX}_{\text{REV}}$ inhibitor.
Keywords
PPADS tetrasodium, 192575-19-2, P2X Receptor, Na+/Ca2+ Exchanger, P2XRs, guinea, pig, airway, smooth, muscle, exchanger, glomerular, mesangial, cell, ATP-sensitive
References
[1] Flores-Soto E, et al. PPADS, a P2X receptor antagonist, as a novel inhibitor of the reverse mode of the Na⁺/Ca²⁺ exchanger in guinea pig airway smooth muscle. Eur J Pharmacol. 2012 Jan 15;674(2-3):439-44.
[2] Huo H, et al. Mapping the binding site of the P2X receptor antagonist PPADS reveals the importance of orthosteric site charge and the cysteine-rich head region. J Biol Chem. 2018 Aug 17;293(33):12820-12831.
[3] Einfluss von ATP und seinen Derivaten auf die Aktivierung von Monozyten.
[4] Rost S, et al. P2 receptor antagonist PPADS inhibits mesangial cell proliferation in experimental mesangialproliferative glomerulonephritis. Kidney Int. 2002 Nov;62(5):1659-71.