Mastoparan inhibits rat renal NaK-ATPase activity

Clinical manifestations of wasp stings: a case report and a review of literature

Background

Wasp stinging, a neglected tropical entity can have a myriad of local and systemic effects. We present a case of multi-organ injury following multiple wasp stings and a review of literature on the systemic manifestations of wasp stings.

Case presentation

A 48-year-old Sri Lankan male who suffered multiple wasp stings, developed an anaphylactic shock with respiratory failure, which was treated with adrenaline and mechanical ventilation. Within the next 2 days the patient developed acute fulminant hepatitis, stage III acute kidney injury, rhabdomyolysis, haemolysis and thrombocytopenia. The patient was treated in the intensive care unit with ionopressors and continuous renal replacement therapy (CRRT). Haemoadsorbant therapy was used in adjunct with CRRT. There was a gradual recovery of the organ functions over the 1st week. However, the patient succumbed to fungal sepsis on the 16th day despite treatment. We conducted a literature review to identify the various clinical manifestations of wasp stinging. Wasp venom contains enzymes, amines, peptides and other compounds. These proteins can cause type 1 hypersensitive reactions ranging from local skin irritation to anaphylactic shock. Furthermore, the toxins can cause direct organ injury or delayed hypersensitivity reactions. The commonly affected organs are the kidneys, liver, and muscles. The effect on the haematological system manifests as coagulopathy and/or cytopenia. The heart, nervous system, lungs, intestines and skin can be affected rarely. Treatment is mainly supportive.

Conclusion

In conclusion, wasp envenomation can result in multi-organ injury and attention should be paid in doing further research and establishing evidence-based treatment practices.

A galanin-mastoparan chimeric peptide activates the Na+,K(+)-ATPase and reverses its inhibition by ouabain

The effect of the neuropeptide galanin, the wasp venom toxin amphiphilic peptide toxin mastoparan and the chimeric peptide, galparan, consisting of N-terminal 13 amino acids of neuropeptide galanin linked at C-terminus to mastoparan amide (and its inactive analog Mas17) on the activity of Na+,K(+)-ATPase has been studied. Mastoparan inhibits the activity of the Na+,K(+)-ATPase with IC50 = 7.5 microM and also reduces the cooperativity for Na+ and K+, respectively, while galanin has no effect on the Na+,K(+)-ATPase activity. The chimeric peptide, galanin(1-13)-mastoparan amide (galparan), exhibits biphasic interaction with Na+,K(+)-ATPase, it activates the enzyme at maximal stimulating concentration of 4 microM followed by inhibition of the enzyme with IC50 of 100 microM. At maximum stimulating concentration (4 microM), galparan partly reduces the cooperativity only for Na+ and it also counteracts the inhibitory effect of oubain on Na+,K(+)-ATPase. Galparan's stimulatory effect was influenced by ATP. The chimeric peptide [19Lys,26Leu]-galparan, containing the inactive analog of mastoparan (Mas17), has no effects on rat brain Na+,K(+)-ATPase activity. Both chimeric peptides galparan and [19Lys,26Leu]-galparan are high-affinity galanin receptor ligands with IC50 of 6.4 nM and 0.71 nM, respectively, while galanin (1-13) and mastoparan alone have significantly lower affinity for the galanin receptor, IC50 of 125 nM and 1 microM, respectively. The ability of chimeric peptides to bind to galanin receptors does not correlate with their effects on the Na+,K(+)-ATPase.

Mastoparan stimulates insulin secretion from pancreatic beta-cells by effects at a late stage in the secretory pathway

Mastoparan (MP) is a component of wasp venom which stimulates secretion from a number of cell types. We have used intact and electrically permeabilised islets of Langerhans to investigate the mechanisms through which MP stimulates insulin secretion from pancreatic beta-cells. MP caused a temperature-dependent and dose-related stimulation of insulin secretion from intact islets at a substimulatory concentration (2 mM) of glucose, which was not dependent upon the presence of extracellular Ca2+. MP also stimulated ATP-independent insulin secretion from electrically permeabilised islets in which intracellular Ca2+ was clamped at a substimulatory concentration (50 nM). MP-induced insulin secretion was not inhibited by down-regulation of islet protein kinase C, nor by the protein kinase inhibitor staurosporine, nor by the cyclic AMP antagonist Rp-adenosine 3',5'-cyclic phosphorothioate. However, MP-induced secretion from permeabilised islets was inhibited by the presence of guanosine 5'-O-2-thiodiphosphate. These results suggest that MP stimulates insulin secretion by a mechanism that is independent of changes in cytosolic Ca2+ or protein kinase activation, but which is dependent, at least in part, upon activation of a GTP-binding protein at a late stage in the secretory process.