Burgen A S
Br J Pharmacol. 1986 Jun;88(2):451-5. doi: 10.1111/j.1476-5381.1986.tb10223.x.
The binding of N-methylscopolamine (NMS) and carbachol to muscarinic receptors in the rat heart has been measured as a function of ionic strength (mu). The binding of NMS was reduced by 3.69 fold for a 10 fold increase in ionic strength. The binding of carbachol was affected in two ways. Firstly, the proportions of the subsites were changed. Above mu = 0.5 M, the superhigh (SH) subsite was converted into the low (L) subsite and above mu = 0.8 M, the high (H) subsite was also converted into the L subsite. Therefore, at high ionic strength, no agonist-determined subsites can be detected. In addition, increase in ionic strength reduced the binding of carbachol to all subsites and to a much greater extent than for NMS.
已测定了N-甲基东莨菪碱(NMS)和卡巴胆碱与大鼠心脏毒蕈碱受体的结合情况,并将其作为离子强度(μ)的函数。离子强度每增加10倍,NMS的结合减少3.69倍。卡巴胆碱的结合受到两方面影响。首先,亚位点的比例发生了变化。在μ>0.5M时,超高(SH)亚位点转变为低(L)亚位点,在μ>0.8M时,高(H)亚位点也转变为L亚位点。因此,在高离子强度下,无法检测到激动剂决定的亚位点。此外,离子强度增加降低了卡巴胆碱与所有亚位点的结合,且降低程度比NMS大得多。