The water-soluble fraction (<10 kD) of bee venom (Apis mellifera) produces inhibitory effect on apical transporters in renal proximal tubule cells

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

Renal vascular and tubular ion channels and transporters involved in toxin injury are reviewed. Vascular ion channels modulated by animal toxins, which result in haemodynamic alterations and changes in blood pressure, include ENaC/Degenerin/ASIC, ATP sensitive K channels (KATP ), Ca activated K channels (Kca) and voltage gated Ca channels, mostly L-type. Renal tubular Na channels and K channels are also targeted by animal toxins. NHE3 and ENaC are two important targets. NCC and NKCC may be involved indirectly by vasoactive mediators induced by inflammation. Most renal tubular K channels including voltage gated K channels (Kv1), KATP , ROMK1, BK and SK are blocked by scorpion toxins. Few are inhibited by bee, wasp and spider venoms. Due to small envenoming, incomplete block and several compensatory mechanisms in renal tubules, serum electrolyte charges are not apparent. Changes in serum electrolytes are observed in injury by large amount of venom when several channels or transporters are targeted. Envenomings by scorpions and bees are examples of toxins targeting multiple ion channels and transporters.

Fanconi syndrome following honeybee stings

A 32-year-old gentleman was attacked by honey bees about 8 months and immediately afterwards his eyelids, cheeks and pinnae became swollen, red, and tender. However, the patient did not develop any renal or serum sickness symptoms and his physical examination and laboratory investigations were normal. He recovered completely. A week later, while working on his farm, he experienced a sudden loss of muscular tone in all four limbs without losing his consciousness. The medical examination subsequently revealed flaccid quadriparesis associated with a serum potassium of 2.1 mEq/L. He was also found to have hyperchloremic metabolic acidosis with normal anion gap and preserved ability to acidify urine to a pH of 5.5. These findings were suggestive of proximal renal tubular acidosis (Fanconi syndrome). Other abnormalities like hypophosphataemia, hypouricemia, renal glucosuria and high urinary excretion of calcium, phosphorus and uric acid further supported the diagnosis of proximal tubular dysfunction. The renal biopsy revealed dense lymphocytic interstitial infiltrate, a feature often seen in Sjogren's syndrome, in which at least 50% of patients fail to acidify urine. In our patient, thorough search for other causes of proximal renal tubular acidosis was negative.