Evidence that ATP is involved as a co-transmitter in the hypogastric nerve supplying the seminal vesicle of the guinea-pig.

Electrical field stimulation of the guinea-pig seminal vesicle (4 Hz and 16 Hz) produced a biphasic response. The initial rapid twitch response was blocked by desensitisation of the P2-purinoceptor with alpha, beta-methylene ATP. The slower tonic response was blocked by the alpha-adrenoceptor antagonist phentolamine (10 microM). The present results are similar to those found earlier for the guinea-pig vas deferens, indicating that ATP and NA may be released as co-transmitters from hypogastric nerve fibres.