The rat tail-suspension model may be more acceptable for simulating weightlessness than other animal models in the view of its less stressful situation. However, there are problems of injury to the skin and development of abscesses and ischemic necrosis of the tail. Inorder to minimize this traumatic nature of the technique and make longer the suspension period, modifications are made to the Morey-Holton and Wronski's tail-suspension method. The main points are as following: (1) Apart from tincture of Benzoin, tincture of resin is spracyed on the tails, which help to unsmooth the tail surface and firm the attachment of the adhesive tape stripes. (2) The taping places on the tail are changed regularly every 7 days. For this reason, the tail surface is divided into four sides and only two opposite ones (upper and below or left and right) are applied with tape stripes, leaving the other two unattached for the later taping place replacement. (3) The traction force acting on the tail is mainly carried by the tape stripes attached longitudinally with the tail rather than those twining around the tail. These modifications effectively protected the tail from ischemic injures caused by the surrounding tape stripes either by the force acting on the tail or the constriction of the tail as the rat grows. The skin injuries by the irritation or tearing of the tape strips rarely happened and could recovery soon after the taping place replacement. The modified tail-suspension is well tolerated by five groups of male SDstrain rats (10 animals per group)for 90 to 120 days, as evidenced by normal feeding, normal grooming behavier and a continued weight gain kept close to or almost same as that of pair-fed control groups hroughout the suspension period. So it may be a useful model for simulating the effects of long-term weightlessness.
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