Systemic effects of N, N-dimethyl-paraphenylenediamine hydrochloride on phosphate metabolism in innervated and denervated, slow and fast muscles of the rat

Abstract

N, N-dimethyl-paraphenylenediamine (DMPPD) hydrochloride increases the inorganic and organic acid-soluble phosphate (P₁ and POAS) uptakes in the innervated gastrocnemius muscle of the rat but not in the innervated soleus. In the denervated gastrocnemius muscle, the effects of DMPPD and denervation are not additive, P₁ uptake being even lower than on the controlateral innervated side. It is suggested that DMPPD acts only on the innervated fast fibre (white fibre, type II anaerobic fibre), as far as the permeability to P₁ is concerned. Histological evidence of a severe myopathic process affecting slow and fast fibres, irrespective of denervation has been documented. Severe degenerative changes were still manifest after a 20-day DMPPD treatment. There is no obvious relation between the biochemical alterations in phosphate metabolism and the morphological lesions.

The increased P₁ and POAS uptakes observed in the innervated gastrocnemius and soleus muscles during generalized convulsions induced by DMPPD are independent of a direct drug action on the muscle fibre.