Studies in sheep examining plasma follistatin elevations due to frequent blood sampling or surgery.

UNLABELLED: This study examined the effects of the anticoagulant heparin on plasma follistatin (FS) concentrations used during blood sampling in Corriedale ewes. Plasma FS concentrations increased acutely (P < 0.01) following a bolus intravenous injection of heparin (3200 U). To determine whether frequent sampling per se can also increase plasma FS concentrations, ewes were sampled using a substitute anticoagulant, ethylenediamine tetraacetic acid. Frequent sampling had no effect on plasma FS concentrations. alpha-2 Macroglobulin concentrations were measured before and after bilateral ovariectomy and sham ovariectomy to determine whether this agent causes an increase in plasma FS concentrations 10-12 h after laparotomy. No differences in plasma alpha-2 macroglobulin concentrations were observed at the time of the observed increase in plasma FS concentrations. IN
CONCLUSION: (1) heparin caused acute elevations in plasma FS concentrations probably by binding to FS, thereby reducing its plasma clearance; (2) rapid blood sampling per se did not elevate plasma FS concentrations; (3) alpha-2 macroglobulin concentrations were not elevated at the same time as plasma FS concentrations 10-12 h after surgery; and (4) the small increase in alpha-2 macroglobulin concentrations before surgery was attributable to a stress-induced response as seen in other species.