Human chorionic gonadotropin directly and indirectly alters uterine arteriolar diameters in cycling rats.
OBJECTIVE
Our purpose was to investigate whether uterine microvascular responses to human chorionic gonadotropin application depend on route of administration and estrous cycle day.


METHODS
One uterine horn was exteriorized in pentobarbital-anesthetized cycling and ovariectomized rats and superfused with Krebs solution Uterine arterioles (64 +/- 2.1 microns) were viewed by videomicroscopy. Diameters were measured during a 20-minute baseline period and for 60 minutes during human chorionic gonadotropin suffusion (20 IU/60 ml) or 60 minutes after intraperitoneal injection of 50 IU of human chorionic gonadotropin. Papaverine (100 mumol/L) suffusion maximally dilated the uterine arterioles (80 +/- 2.6 microns).


RESULTS
Suffusion of human chorionic gonadotropin-dilated arterioles on diestrus-1 (122% +/- 2% baseline) and diestrus-2 (118% +/- 4% baseline) but constricted arterioles on proestrus (78% +/- 7% baseline). Intraperitoneal injection of human chorionic gonadotropin resulted in arteriolar constriction on diestrus-2 (76% +/- 5% baseline) and proestrus (82% +/- 3% baseline). Ovariectomy eliminated the effects of injected but not suffused human chorionic gonadotropin. All results are significant at p < 0.05.


CONCLUSIONS
Results indicate estrous cycle day-dependent direct and indirect effects of human chorionic gonadotropin on the resistance of uterine arterioles.
Hill
J B
JB
Center of Excellence for Applied Microcirculatory Research, University of Louisville, KY 40292, USA.
Alsip
N L
NL
Rao
C V
CV
Asher
E F
EF
D000818:Animals; D001160:Arterioles / Q000033:anatomy & histology / Q000187:drug effects; D006063:Chorionic Gonadotropin / Q000008:administration & dosage*; D004971:Estrus; D005260:Female; D006801:Humans; D008297:Male; D010208:Papaverine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014599:Uterus / Q000098:blood supply* / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
D006063:Chorionic Gonadotropin; D014665:Vasodilator Agents; D010208:Papaverine