4.3. Animals

The animal tests were performed with the approval of the ethical committee of the University of Oulu. All aspects of animal care complied with the Animal Welfare Act and the recommendations of the NIH-PHS Guide for the Care and Use of Laboratory Animals.

All the animals used were female Sprague-Dawley/MOL rats from the Laboratory Animal Centre, University of Oulu (Oulu, Finland). In studies II and III same rats were used. The ages of the rats ranged between 20 and 24 weeks with a weight range of 320 to 380 g. Seventy-five rats were randomized into 3 groups, each consisting of 25 rats. In study IV, the ages of the test animals ranged between 32 and 36 weeks. Forty rats were randomized into 2 groups, each consisting of 20 rats. The mean weight was 486 ± 65 g (mean ± 1SD) in the StSt group and 473 ± 52 g in the NiTi group. All the animals were housed in groups of 3 - 6 in Macrolon IV polycarbonate cages in a thermostatically controlled room at 20 ± 1 C with a relative humidity of 50 ± 10%. The room was artificially illuminated on a schedule of 12 h of light and 12 h of darkness. Aspen chips (Fintapway, Finland) were used as bedding. Pelleted rat feed (SDS R3(E), Special Diet Services Ltd., Great Britain) and tap water were available ad libitum.