Examining Uterine Endometrial Blood Perfusion Using a Novel Laser Doppler Technique in Angus Cows

The objective was to determine endometrial blood perfusion and hormone enzyme activity contralateral and ipsilateral to both the corpus luteum (CL) and developing dominant follicle (DF). Fourteen Angus cows were subjected to an Ovsynch + CIDR estrous synchronization protocol with d 0 corresponding to day of estrus. Equine AI rods were passed through the cervices, which provided a canal for the laser Doppler probe (PeriFlux 5000 LDPM, Perimed Inc., Ardmore, PA) to collect endometrial blood perfusion and microvascular flow of tissue surfaces without traumatizing the endometrium. Optimal perfusion was obtained by selecting 10 s of relatively constant perfusion for measurement, as measured by arbitrary Perfusion Units (PU) following calibration. After perfusion was collected, cattle were subjected to an endometrial biopsy utilizing a mare uterine biopsy punch with a sample collected from each horn and snap frozen. Perfusion and uterine biopsies were collected on d 12, 15, 18, and 21 of the estrous cycle. Data were analyzed using repeated measures ANOVA of the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC), using the Wilcoxon rank sum test, and significance was declared at P ≤ 0.05. The model statement included day of estrous cycle, CL and DF location (respective to each uterine horn), the respective interactions with day, and CL and DF size with their respective interactions with day as covariants. Cattle were subjected to ultrasonography on d 11 and 19 of the estrous cycle to determine CL and follicular locations and size. Uterine biopsies were homogenized and activity of uridine 5’-diphospho-glucuronosyltransferase (UGT) was determined via luminogenic substrates (expressed per mg of protein). No differences (P ≥ 0.15) in endometrial perfusion were observed based on the location of the CL. However, endometrial perfusion was greater (P < 0.01) on the ipsilateral side to the DF. No differences (P ≥ 0.34) in endometrial perfusion were observed within day. Finally, no differences (P ≥ 0.38) were observed for UGT activity. In conclusion, endometrial perfusion relative to location of the DF were different whereas the CL location did not influence blood perfusion or UGT activity. This alteration in endometrial perfusion could be due to an increase in estrogen due to the presence of the DF.