Cardiovascular assessment in radiotelemetry-implanted pregnant rats

The aim of this study was to assess the potential adverse effects of the chronic use of surgically implanted radiotelemetry transmitters and femoral catheters on embryo-fetal development in rats.

Two groups of 10 female rats were implanted with femoral catheters and radiotelemetry transmitters. Ten additional rats were implanted with femoral catheters alone. The females were then time mated with male rats and pregnancy confirmed. Saline was continuously infused from gestation days 6-17. Saline infusion was replaced with 0.8 μg/ml angiotensin II in one group of animals, on gestation days 6, 9, 12, and 15 in order to demonstrate the validity of the system to detect changes in hemodynamic function by a pharmacologically active agent. Embryo-fetal development was assessed by examination of the number and location of the fetuses, early and late resorptions, and number of implantation sites. Parameters evaluated included postimplantation loss, live litter size, mean fetal body weights, and fetal sex ratios.

Intrauterine survival was unaffected in all groups. Mean numbers of corpora lutea and implantation sites and the mean litter proportions of preimplantation loss were similar across all groups. Infusion of angiotensin II elicited the expected hemodynamic response, i.e., increased arterial blood pressure with a concomitant decrease in heart rate.

Radiotelemetry can be used in combination with continuous intravenous infusion as a viable methodology for detecting test article induced changes in cardiovascular function in pregnant rats, with no effects on intrauterine growth and survival or fetal morphology.