The effects of stimulating the intramural nerves on the membrane potential and tension in the uterine artery of virgin @entity840 were compared with the responses during pregnancy. In all tissues the amplitude of the excitatory junction potential (EJP) increased as the stimulus voltage was increased. The rate of increase in EJP amplitude in tissues from virgin animals greatly exceeded that recorded in late pregnant tissues. EJPs were abolished by @entity1022 but were resistant to blockade by alpha-adrenoceptor antagonists. Stimulation of the nerves also evoked a slow depolarization and contraction which were abolished by both @entity1022 and alpha-adrenoceptor antagonists. The amplitudes of the depolarizations and contractions were not correlated. The role of EJPs and alpha-adrenoceptor activation in the control of vascular function is discussed. Fluorescence histochemistry revealed a decrease in the density of the @entity2922 innervation that was correlated with a decrease in @entity2922 content as pregnancy progressed. In addition, there appeared to be a difference in the arrangement of the fluorescent varicosities, with a shift from varicosities that were close to the outer layer of smooth muscle in virgin tissues to those that were more distantly dispersed in the adventitia during late pregnancy. The changes would be expected to reduce the effectiveness of vasoconstrictor drive to the uterine artery as pregnancy progresses.

Pregnancy-induced decrease in evoked excitatory junction potentials in XXXX uterine artery.

@entity840 :: ('10141', 'Species') :: ['guinea pigs'] @entity1022 :: ('MESH:D013779', 'Chemical') :: ['tetrodotoxin'] @entity2922 :: ('CHEBI:33567', 'Chemical') :: ['catecholamine']
@entity840 :: (10141,Species) :: ['guinea pig']
