Some effects of purines on neurones of guinea-pig superior cervical ganglia.

1. The actions of adenosine 5'-triphosphate (ATP) and related purine analogues on neurones of isolated superior cervical ganglia in guinea-pig were studied using intracellular recording techniques. 2. Application of ATP (0.1-1 mM) by superfusion evoked a response in half (26 out of 52) of the neurones studied. The response consisted of a slow depolarization (in 23 of the cells) or a hyperpolarization (in 3 cells). The amplitude of depolarization was concentration-dependent and was accompanied by a decrease in input resistance (in 12 of 23 responses). 3. Superfusion of the P2 chi-purinoceptor selective agonist alpha, beta-methylene ATP (1-100 microM), evoked a response in the majority (42 of 58) of neurones studied. The response consisted of a depolarization (in 39 cells) or a hyperpolarization (in 3 cells). The depolarization was also concentration-dependent and was accompanied by a decrease in input resistance (36 of 39 responses). Superfusion of another P2 chi-purinoceptor agonist, beta, gamma-methylene ATP (10 microns), also produced a small depolarization (5 of 8 cells) which was accompanied by a decrease in input resistance. 4. Application of the P2 gamma-purinoceptor selective agonist, 2-methylthio ATP (1-100 microM) evoked a response in approximately half (28 of 55) of the neurones studied. The response consisted of a depolarization (in 23 cells) or a hyperpolarization (in 5 cells). The amplitude of the depolarization was concentration-dependent and accompanied by a decrease in input resistance (13 of 21 responses). 5. Superfusion of the P1-purinoceptor selective agonist 2-chloroadenosine (100 microM) evoked a response in only a few (3 of 21) of the neurones tested.(ABSTRACT TRUNCATED AT 250 WORDS)