Uppal S K, Wolf K, Martens H
Department of Clinical Veterinary Medicine, E & J, Punjab Agricultural University, Ludhiana, India.
J Anim Physiol Anim Nutr (Berl). 2003 Feb;87(1-2):12-20. doi: 10.1046/j.1439-0396.2003.00401.x.
The present in vitro experiment was conducted to study the effect of two concentrations of short chain fatty acids [SCFA: 0 (control), 40 and 100 mmol/l in the buffer solution on mucosal side] on calcium ion (Ca2+) transport across the isolated rumen epithelium of two groups of sheep. One group was subjected to hay ad libitum, whereas the other to concentrate feed (800 g per day in equal portion at 7.00 and 15.00 hours and hay ad lib). The conventional Ussing chamber method was used for measuring the Ca2+ transport rates (45Ca), short-circuit current (Isc) and tissue conductance (GT) of isolated rumen epithelium. The SCFA significantly increased Isc of the epithelia of concentrate-fed sheep. In both hay- and concentrate-fed animals, 45Ca flux rates showed an almost linear increase in net flux rate () with rising concentrations of SCFA, as a result of a combined effect of a large increase in mucosal-to-serosal flux rates () and an almost linear, but small, decrease in serosal-to-mucosal flux rate (). In concentrate-fed sheep and were significantly higher in tissues incubated with SCFA compared with hay-fed animals. The well-known adaptable morphological and functional changes in the rumen epithelium attributable to concentrate feeding obviously include Ca2+ transport; such feeding therefore may be considered as a possible prophylactic measure in the prevention of milk fever.
本体外实验旨在研究两种浓度的短链脂肪酸[SCFA：缓冲溶液黏膜侧浓度分别为0（对照）、40和100 mmol/L]对两组绵羊离体瘤胃上皮钙离子（Ca2+）转运的影响。一组随意采食干草，另一组饲喂精饲料（每天800 g，于7:00和15:00等份投喂，同时自由采食干草）。采用传统的Ussing chamber法测量离体瘤胃上皮的Ca2+转运速率（45Ca）、短路电流（Isc）和组织电导（GT）。SCFA显著增加了精饲料喂养绵羊上皮的Isc。在采食干草和精饲料的动物中，由于黏膜到浆膜通量速率（）大幅增加和浆膜到黏膜通量速率几乎呈线性但小幅下降的综合作用，45Ca通量速率显示随着SCFA浓度升高净通量速率（）几乎呈线性增加。与采食干草的动物相比，在添加SCFA孵育的组织中，精饲料喂养绵羊的和显著更高。精饲料喂养导致瘤胃上皮出现众所周知的适应性形态和功能变化，显然包括Ca2+转运；因此，这种喂养方式可被视为预防产乳热的一种可能的预防措施。
