Changes in intrafollicular pressure in the rat ovary by nitric oxide and by alteration of systemic blood pressure.
BACKGROUND
ovulation is associated with degradation of the follicular apex vasodilatation and increased permeability of ovarian vessels. These changes may maintain or increase intrafollicular pressure (IFP) at ovulation to cause rupture of the follicular wall.


OBJECTIVE
to investigate the possible regulation of IFP during the ovulatory process.


METHODS
immature Sprague-Dawley rats were primed with pregnant mare serum gonadotrophin (PMSG; 10IU) and given hCG (10IU) 48h later. The ovary was exposed 48-60h after PMSG, micropipette inserted into the Graafian follicle and the IFP measured at three time periods: preovulatory (PO) 48h after PMSG; midovulatory (MO) 4-7h after hCG; late ovulatory (LO) 9-12h after hCG. The offset of the nitric oxide synthase (NOS) inhibitor L-arginine methyl ester (L-NAME), the alpha(1)-adrenoceptor agonist phenylephrine and the beta-adrenoceptor agonist isoprenaline were tested.


RESULTS
phenylephrine given i.v. increased the systemic blood pressure, and significantly decreased the IFP in the LO phase (78% of pre-treatment value). Local administration of phenylephrine or isoprenaline (1ml of 1.5-15 microM) by superfusion over the ovary did not change the IFP. Local administration of L-NAME (1ml of 2 microM) significantly lowered (P<0.05) the IFP in the MO and LO phases, but was without effect in the PO phase.


CONCLUSIONS
this study reveals that IFP regulation may be related to changes of the systemic blood pressure and that NO may be one local ovarian mediator in IFP regulation.
Matousek
M
M
Department of Obstetrics and Gynaecology, Göteborg University, Sahlgrenska University Hospital, S-413 45, Göteborg, Sweden. markus.matousek@sahlgrenska.se
Carati
C
C
Gannon
B
B
Mitsube
K
K
Brännström
M
M
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D006080:Ovarian Follicle / Q000187:drug effects* / Q000502:physiology*; D010060:Ovulation / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D011941:Receptors, Adrenergic / Q000187:drug effects / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D006063:Chorionic Gonadotropin; D004791:Enzyme Inhibitors; D006064:Gonadotropins, Equine; D011941:Receptors, Adrenergic; D010656:Phenylephrine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D007545:Isoproterenol; D019331:NG-Nitroarginine Methyl Ester