Gudbjarnason S, Benediktsdóttir V E
University of Iceland, Science Institute, Reykjavik.
J Mol Cell Cardiol. 1995 Jan;27(1):243-51. doi: 10.1016/s0022-2828(08)80023-5.
The purpose of this study was to examine changes in binding properties of alpha 1-adrenoceptors, beta-adrenoceptors and L-Ca channels in rat heart muscle in relation to changes in the lipid environment within the membrane, i.e. fatty acyl chain composition of membrane phospholipids, occurring during repeated adrenergic stimulation. The effect of daily administration of epinephrine for seven days upon the maximum number of binding sites of adrenoceptors and upon the fatty acyl chain composition of phosphatidylcholine and phosphatidylethanolamine was examined in 10 months old rats. Decrease in Bmax of adrenoceptors during repeated adrenergic stimulation coincided with remodeling of the membrane phospholipids, with replacement of 18:2n-6 by 20:4n-6 in phosphatidylcholine and by 22:6n-3 in phosphatidylethanolamine, respectively. The effect of repeated adrenergic stimulation was also examined in rats fed different dietary fats and oils, i.e. butter, corn oil or cod liver oil, in hearts with markedly different levels of 18:2n-6, 20:4n-6 and 22:6n-3. The binding properties of the adrenoceptors and L-Ca channels did not relate to the fatty acyl chain composition of bulk phospholipids, but the epinephrine induced decrease in Bmax of the receptors was always accompanied by replacement of 18:2n-6 by 20:4n-6 in phosphatidylcholine and by 22:6n-3 in phosphatidylethanolamine, regardless of the initial level of these fatty acyl chains in the phospholipids. It is concluded that adaption to repeated adrenergic stimulation may include coregulation of the lipid environment within the membrane and the binding properties of adrenoceptors, and possibly other functionally coupled proteins such as L-Ca channels, residing in the membrane.
本研究的目的是检测大鼠心肌中α1 -肾上腺素能受体、β -肾上腺素能受体和L -钙通道的结合特性变化，这些变化与反复肾上腺素能刺激期间膜内脂质环境的变化相关，即膜磷脂的脂肪酰链组成。在10月龄大鼠中检测了连续7天每日给予肾上腺素对肾上腺素能受体结合位点最大数量以及磷脂酰胆碱和磷脂酰乙醇胺脂肪酰链组成的影响。反复肾上腺素能刺激期间肾上腺素能受体的Bmax降低与膜磷脂重塑同时发生，磷脂酰胆碱中18:2n - 6分别被20:4n - 6取代，磷脂酰乙醇胺中18:2n - 6被22:6n - 3取代。还在喂食不同膳食脂肪和油（即黄油、玉米油或鱼肝油）的大鼠中检测了反复肾上腺素能刺激的影响，这些大鼠心脏中18:2n - 6、20:4n - 6和22:6n - 3的水平明显不同。肾上腺素能受体和L -钙通道的结合特性与总体磷脂的脂肪酰链组成无关，但无论磷脂中这些脂肪酰链的初始水平如何，肾上腺素诱导的受体Bmax降低总是伴随着磷脂酰胆碱中18:2n - 6被20:4n - 6取代，磷脂酰乙醇胺中18:2n - 6被22:6n - 3取代。得出的结论是，对反复肾上腺素能刺激的适应可能包括膜内脂质环境与肾上腺素能受体结合特性的共同调节，以及可能包括膜中其他功能偶联蛋白，如L -钙通道。
