Arginase has been suggested to play an important role in cellular growth and development, particularly important to the fetus, by supplying L-ornithine for the synthesis of polyamines. The purpose of this investigation was to determine whether pregnancy alters myometrial arginase activity and whether estradiol was responsible for the change.
Myometrium and kidney were obtained from nonpregnant and pregnant guinea pigs of known gestational age. Arginase activity was measured under physiologic conditions by the conversion carbon 14-labeled guanidino-L-arginine to carbon 14-labeled urea. The concentrations of the enzyme's substrate, L-arginine, and its principal metabolite, L-ornithine, were measured in myometrium from near-term pregnant animals by use of an amino acid analyzer. Finally, a group of random cycle guinea pigs received 500 microgram/kg estradiol for 5 days before the myometrium was removed.
Myometrial arginase activity in pregnant animals was more than double that of myometrium from nonpregnant animals by the time the first measurement was made at 0.14 gestation. It continued to rise, peaking at values >25-fold higher than the nonpregnant activity by 0.90 gestation. Arginase activity in the myometrium underlying the placental implantation site was >25 fold higher (p<0.05) than myometrium from nonpregnant animals when first studied at 0.63 gestation and 10-fold higher than the contralateral fundal myometrium at the same time of gestation. Myometrial arginase activity in the sterile horn of six pregnant animals was half that of the horn containing one or more pups, but still five times higher than that of nonpregnant animals. Renal arginase activity also rose with advancing pregnancy, but the magnitude of the increase (up to 2-fold) was much smaller than that observed in either the fundal or placental implantation site myometrium. Estradiol had no significant effect on myometrial arginase activity.
These studies demonstrate that pregnancy increases myometrial arginase activity and that the presence of placenta or fetus is necessary for the maximal effect.
Pharmacology, Toxicology and Pharmaceutical Science
1
6%
Other
0
0%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 3. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 15 May 2008.
All research outputs
#12,344,681
of 34,362,729 outputs
Outputs from American Journal of Obstetrics & Gynecology
#9,449
of 17,471 outputs
Outputs of similar age
#32,318
of 117,093 outputs
Outputs of similar age from American Journal of Obstetrics & Gynecology
#37
of 69 outputs
Altmetric has tracked 34,362,729 research outputs across all sources so far. This one is in the 38th percentile – i.e., 38% of other outputs scored the same or lower than it.
So far Altmetric has tracked 17,471 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 16.0. This one is in the 20th percentile – i.e., 20% of its peers scored the same or lower than it.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 117,093 tracked outputs that were published within six weeks on either side of this one in any source. This one is in the 13th percentile – i.e., 13% of its contemporaries scored the same or lower than it.
We're also able to compare this research output to 69 others from the same source and published within six weeks on either side of this one. This one is in the 2nd percentile – i.e., 2% of its contemporaries scored the same or lower than it.
