Involvement Of Oxidative Stress In Bee Venom‐Induced Inhibition Of Na⁺/Glucose Cotransporter In Renal Proximal Tubule Cells

Abstract

1. The present study was conducted to examine the involvement of oxidative stress in bee venom-induced inhibition of the Na+/glucose cotransporter (alpha-methyl-d-glucopyranoside (alpha-MG) uptake), a typical functional marker of proximal tubules, in primary cultured rabbit renal proximal tubule cells (PTC). 2. Bee venom (> or = 1 microg/mL) increased lipid peroxide (LPO) formation over 30 min. The increase in [(3)H]-arachidonic acid (AA) release and LPO formation and the inhibition of alpha-MG uptake induced by bee venom (1 microg/mL) and melittin (a major component of bee venom; 0.5 microg/mL) were blocked by N-acetyl-l-cysteine, vitamin C and vitamin E, anti-oxidants. 3. Bee venom- and melittin-induced increases in LPO formation and inhibition of alpha-MG uptake were significantly prevented by mepacrine and AACOCF(3), phospholipase A(2) inhibitors. In addition, nordihydroguaiareic acid (a lipoxygenase inhibitor) and econazole (a cytochrome P-450 epoxygenase inhibitor), but not indomethacin (a cyclo-oxygenase inhibitor), prevented bee venom- and melittin-induced increases in LPO formation and inhibition of alpha-MG uptake. 4. Nordihydroguaiareic acid prevented bee venom- and melittin-induced increases in Ca(2+) uptake. Moreover, anti- oxidants significantly prevented bee venom- and melittin-induced increases in Ca(2+) uptake. 5. In conclusion, bee venom inhibits alpha-MG uptake via the phospholipase A(2)-oxidative stress-Ca(2+) signalling cascade in primary cultured rabbit renal proximal tubule cells.

Melittin stimulates fatty acid release through non-phospholipase-mediated mechanisms and interacts with the dopamine transporter and other membrane-spanning proteins

“…Surprisingly the general phospholipase A 2 inhibitor quinacrine (Demuth et al, 2005) was also without effect on melittin-induced [ 3 H]arachidonic acid release (Fig 4E). Phospholipase A 2 inhibitors successfully block melittin-induced release of arachidonic acid in rabbit proximal tubule cells (Han et al, 2002), but quinacrine is unable to inhibit melittin-induced release of arachidonic acid in rat Leydig cells (Ronco et al, 2002). …”

“…Thus, melittin did not act as a specific pharmacological stimulator of phospholipases. This effect may be particular to the chosen cell type, as phospholipase A 2 inhibitors successfully block melittin-induced release of arachidonic acid in rabbit proximal tubule cells (Han et al, 2002), but quinacrine is unable to inhibit melittin-induced release of arachidonic acid in rat Leydig cells (Ronco et al, 2002). Further, it is suggested that melittin has no inherent phospholipase activity, and that fatty acids are released subsequent to the membrane perturbations following melittin incorporation and pore formation (Raghuraman and Chattopadhyay, 2007).…”

Recovery from AKI Following Multiple Wasp Stings

“…Bee venom, which has been studied to a greater extent than the venom of other species within the order Hymenoptera, contains melittin, phospholipase A2 (PLA2), mast cell-degranulating peptide (peptide 401), hyaluronidase, and apamin, among other constituents (1). Melittin, which makes up approximately 50% of the entire bee venom mixture (14), powerfully disrupts cell membranes and has direct toxic effects on renal tubular cells of the host (15)(16)(17). Wasp venom does not contain melittin.…”

Animal toxins and renal ion transport: Another dimension in tropical nephrology

“…Melittin inhibits proximal tubular reabsorption of α methyl D‐glucopyranoside, aminoacid and phosphate . Inhibition of α methyl D‐glucopyranoside by melittin is through lipid peroxidation and increased arachidonic acid and is prevented by mepacrine and AACOCF3, PLA2 inhibitors . Melittin is a strong PLA 2 stimulator and inhibits NHE3 either directly or through Na K‐ATPase inhibition or through 20‐HETE.…”