Vitamin PP, nicotinamide nucleotides and neuro-muscular transmission in guinea pig cecum longitudinal muscle (taenia coli)

The membrane potential, inhibition postsynaptic potentials, resistance of the guinea pig taenia coli membrane were studied as affected by exogenic vitamin PP and its derivatives of nucleotide nature. It is shown that nicotinic acid, nicotinamide, NAD+, NADH, NADP+, NADPH evoke the membrane hyperpolarization and a decrease in the amplitude of the inhibition postsynaptic potentials. Nicotinamid dinucleotides cause a decrease in the membrane resistance, whereas nicotinic acid and nicotinamide do not affect this parameter. The character of the observed effects does not depend on the degree of nicotinamide dinucleotides oxidation.