Effects of estrogen and progestin on the CO2 sensitivity of hemispheric cerebral blood volume.
OBJECTIVE
High CO2 sensitivity is one of the major characteristics of the cerebrovascular bed. It has been shown to be influenced by many differrent factors (eg, sex hormones).


METHODS
The effect of ovariectomy and subsequent female sexual hormone treatment on the steady-state hemispheric cerebral blood volume and CO2 responsiveness of the hemispheric blood vessels was studied on anesthetized, ventilated, normotensive, normoxic rats. Cerebral blood volume was measured with Tomita's photoelectric method with Sandor's modification.


RESULTS
Steady-state cerebral blood volume values in ovariectomized rats did not differ from those found in control animals. The CO2 responsiveness of hemispheric blood vessels was higher in ovariectomized and progestin-treated, but not estrogen-treated, animals compared with controls.


CONCLUSIONS
Our results demonstrate that the CO2 sensitivity of the hemispheric vessels is sex hormone dependent. Estrogen and progestin treatment have opposite effects on this cerebral circulatory parameter.
Szelke
Emese
E
Institute of Human Physiology and Clinical Experimental Research, Semmelweis University, Budapest, Hungary.
Mersich
Tamás
T
Szekacs
Bela
B
Sandor
Peter
P
Komjati
Katalin
K
Varbiro
Szabolcs
S
D000818:Animals; D001784:Blood Gas Analysis; D001810:Blood Volume; D002245:Carbon Dioxide / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects* / Q000502:physiology; D054022:Cerebrum / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism; D004195:Disease Models, Animal; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D010052:Ovariectomy; D017698:Postmenopause; D011372:Progestins / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D004967:Estrogens; D011372:Progestins; D002245:Carbon Dioxide