Effects of adenosine analogues on guinea-pig endometrial secretion

The effect of adenosine analogues on guinea-pig endometrial secretion was studied in vitro at defined days of the estrous cycle. The adenosine analogues, 5′-N-ethylcarbox-amideadenosine (NECA) and (N⁶-[(R)-1-methyl-2-pheny!ethyl]-adenosine (R-PIA), induced endometrial secretion at ovulation time (cycle days 16-1) and at implantation time (cycle days 6-7). The secretory response to NECA was antagonized by 8-p-sulfophenyltheophylline. Scopolamine had no effect on secretion induced by the adenosine analogues. Endometrial secretion induced by field stimulation was inhibited by NECA but not by R-PIA at ovulation time. At implantation time, both NECA and R-PIA reversed the response to field stimulation to values below the basal resting level. The latter effect was antagonized by phentol-amine. These findings suggest that adenosine analogues can induce guinea-pig endometrial secretion by action at stimulatory adenosine receptors, and concomitantly inhibit secreto-motor neurotransmission.