Contractility of late pregnant rat myometrium is refractory to activation of soluble but not particulate guanylate cyclase.
OBJECTIVE
Our purpose was to compare the effects of agents activating particulate or soluble guanylate cyclases on the spontaneous contractile activity of the isolated pregnant rat uterus.


METHODS
Uterine rings from midpregnant (14-day) and late pregnant (21-day) rats were suspended in organ chambers to record spontaneous contractile activity. Concentration-response curves were obtained for the following natriuretic peptides: atrial, brain, and C-type; concentration-response curves were also obtained for diethylamine nitric oxide, 3-morpholino-sydnominine, and authentic nitric oxide.


RESULTS
All 3 natriuretic peptides inhibited spontaneous uterine contractions equally at midgestation and late gestation. The inhibitory effects of the nitric oxide donors diethylamine nitric oxide, 3-morpholino-sydnominine, and authentic nitric oxide were attenuated in uterine tissues from animals in late stages of pregnancy.


CONCLUSIONS
Agents activating either soluble or particulate guanylate cyclase inhibit contractions of uterine rings from midgestation rats, whereas the effects of soluble guanylate cyclase are attenuated at late pregnancy. Thus spontaneous uterine contractions are under the control of both soluble and particulate guanylate cyclases; the former is dependent on gestational age but the latter is not.
Fulep
E
E
Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, USA.
Vedernikov
Y
Y
Saade
G R
GR
Garfield
R E
RE
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005260:Female; D006162:Guanylate Cyclase / Q000737:chemistry* / Q000378:metabolism*; D006834:Hydrazines / Q000008:administration & dosage / Q000494:pharmacology; D008981:Molsidomine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D020097:Natriuretic Peptide, Brain / Q000008:administration & dosage / Q000494:pharmacology; D020098:Natriuretic Peptide, C-Type / Q000008:administration & dosage / Q000494:pharmacology; D009569:Nitric Oxide / Q000008:administration & dosage / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000008:administration & dosage / Q000494:pharmacology; D009589:Nitrogen Oxides; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility; D014590:Uterine Contraction / Q000187:drug effects / Q000502:physiology*
D006834:Hydrazines; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D020097:Natriuretic Peptide, Brain; D020098:Natriuretic Peptide, C-Type; D009569:Nitric Oxide; C002385:linsidomine; D009320:Atrial Natriuretic Factor; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D008981:Molsidomine; D006162:Guanylate Cyclase