Effects of delta-aminolaevulinic acid upon electrical activity of rat spinal cord in vivo.

Bath applied delta-aminolaevulinic acid (ALA, 1-1000 microM), significantly depressed the frequency of spontaneous antidromic activity in the lumbar dorsal roots, and the amplitude of the monosynaptic component of the dorsal root-evoked ventral root reflex, in isolated rat spinal cord in a concentration-related manner. In contrast bath concentrations up to 1 mM ALA were found to produce no significant change in either the conducted afferent volley, nor field potentials recorded in the lumbar dorsal horn. These results indicate that the raised levels of ALA found in cerebrospinal fluid during porphyrias and lead poisoning may contribute to the neurological symptoms of these diseases.