Role of chloride in hypertonicity-induced contractures of rat soleus muscle

The role of chloride in contractures induced in rat soleus muscle by mannitol-, sucrose- or urea-containing hypertonic solutions was investigated. Replacement of chloride with nitrate, sulphate or perchlorate reduced the amplitude of mannitol- and sucrose-induced contractures, and the first phase of contractures induced by urea. Addition of 9-anthracene carboxylic acid had similar effects. The presence of diazepam increased the amplitude of 'hypertonic' contractures. The results show that chloride is important in the development of hypertonic contractures.