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The influence of ovarian steroids upon responses to electrical stimulation and to activation of adrenoreceptors in field-stimulated preparations of longitudinal and circular myometrium from ovariectomised guinea-pigs has been investigated. Adult virgin guinea-pigs were bilaterally ovariectomised and were treated two weeks later with thrice-weekly injections of oestradiol cypionate for two weeks, or treated as in then given oestradiol cypionate and progesterone for a further four days. Control groups of bilaterally ovariectomised and sham ovariectomised animals remained untreated. Both myometrial layers from untreated ovariectomised guinea-pigs were atrophied. Responses to field stimulation in the circular myometrium were much smaller than those in the longitudinal layer. Steroid pretreatment, most notably treatment with oestradiol and progesterone, were associated with decreased and increased responsiveness to electrical stimulation in the circular and longitudinal myometrial layers respectively. Adrenaline and noradrenaline were consistently excitatory on preparations of circular myometrium from ovariectomised animals. Responses comprised either enhancement of electrically-evoked contractions, or, with the higher concentrations, the appearance of rapid contractions superimposed upon an increase in basal tone. The latter effects were also evident in preparations of circular myometrium from sham operated animals. In preparations of longitudinal myometrium from untreated ovariectomised animals noradrenaline consistently and adrenaline usually caused a simple enhancement of the magnitude of the evoked contractions. Phentolamine reduced the excitatory effects of both amines in both layers. In circular myometrium from the oestrogen-treated group both catecholamines produced phentolamine-sensitive enhancement of electrically-evoked contractions, but did not cause high frequency contractions or increased tonus. Noradrenaline and adrenaline produced qualitatively similar phentolamine-sensitive effects in preparations of longitudinal myometrium from this group.(ABSTRACT TRUNCATED AT 250 WORDS)
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
September 1986,
Journal of autonomic pharmacology,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
December 1981,
European journal of pharmacology,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
November 1987,
European journal of pharmacology,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
February 1972,
Obstetrics and gynecology,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
June 1988,
Agents and actions,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
May 1988,
Research in veterinary science,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
May 1983,
British journal of pharmacology,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
August 1990,
European journal of pharmacology,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
May 1997,
The American journal of physiology,
S P Adam, and
M L Hartley, and
J N Pennefather, and
M E Story, and
G M Handberg
April 1978,
The Journal of endocrinology,
