Scorpion venoms: taking the sting out of lung disease.

Scorpion venoms contain specific toxins which block large conductance calcium-activated potassium (BKCa) channels. Use of these toxins has shown that a significant proportion of the action of bronchodilators such as beta-agonists, theophylline, and nitric oxide occurs as a result of the opening of BKCa channels. Similarly, these toxins have shown that inhibitors of airway neurotransmission also operate via BKCa channels. Drugs that open BKCa channels may be alternative bronchodilators (possibly "airway selective" and with fewer side effects) as well as inhibitors of pathophysiological neurogenic influences in asthma, chronic coughing and sneezing, and chronic bronchitis.