A PREVIOUS study has evaluated the role of 3,4-dihydroxybenzoic acid (3,4-DHBA) (procatechuic acid) in the genesis of the uremic syndrome.1 Like its 2,4-dihydroxy isomer (2,4-DHBA) (β-resorcylic acid), 3,4-DHBA hastened paresis, prostration, and death and contributed to cardiac dysfunction in rats in acute renal failure. Unlike the 2,4-isomer which seemed to produce depression, 3,4-DHBA contributed to exacerbation of signs of nervous system hyperexcitability. Myoclonic jerks, muscle spasms, grand mal seizures, and spontaneous electroencephalographic seizure activity characterized rats receiving 3,4-DHBA. Electroencephalographic and behavioral differences were not clearly correlated with differences in urea or electrolyte concentrations.
The initial investigation, therefore, suggested that 3,4-DHBA produced nervous system hyperexcitability; whereas 2,4-DHBA, differing only in the position of one hydroxyl group, produced neuromuscular depression. The present study was undertaken as an attempt to corroborate these findings by an independent method and to compare the effects of these and related compounds on seizure threshold