ELEVATED INTRACELLULAR CA-2+ ACTS THROUGH PROTEIN KINASE-C TO REGULATE RABBIT ILEAL NACL ABSORPTION - EVIDENCE FOR SEQUENTIAL CONTROL BY CA-2+ CALMODULIN AND PROTEIN KINASE-C
ELEVATED INTRACELLULAR CA-2+ ACTS THROUGH PROTEIN KINASE-C TO REGULATE RABBIT ILEAL NACL ABSORPTION - EVIDENCE FOR SEQUENTIAL CONTROL BY CA-2+ CALMODULIN AND PROTEIN KINASE-C
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DOI：
10.1172/jci114104
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发表时间：
1989-06-01
影响因子：
15.9
通讯作者：
SHARP, GWG
中科院分区：
文献类型：
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作者：
DONOWITZ, M;COHEN, ME;SHARP, GWG
钙/钙调素参与了兔回肠基础钠、氯吸收的调节，但细胞内钙离子升高对钠、氯转运的影响机制尚不清楚。为了研究钙/钙调蛋白和蛋白激酶C系统在回肠氯化钠转运中的作用，两种药物，异喹诺苯磺酰胺H-7和萘磺酰胺W13，分别在回肠绒毛细胞上用磷酸化试验确定了对蛋白激酶C(60微米H-7)和钙/钙调蛋白(45微米W13)的特异性拮抗浓度。W13而不是H-7促进了基础活性盐的吸收。H-7抑制了最大浓度的钙离子载体A23187、氨基甲胆碱和5-羟色胺引起的钠和氯吸收的变化，而W13则没有作用。相反，H-7和W13都不能改变环核苷酸8-溴-cAMP和8-溴-cGMP引起的氯化钠转运的变化。这些结果表明：(A)兔回肠对氯化钠的基础吸收是由钙/钙调蛋白复合体调节的，而不是由蛋白激酶C调节的；(B)升高细胞内钙离子以减少氯化钠吸收的作用是通过蛋白激酶C而不是通过钙/钙调蛋白来实现的；(C)蛋白激酶C与钙/钙调素在基础吸收或增加钙的作用上没有重叠或协同作用；(D)cAMP和cGMP都不参与cAMP和cGMP对回肠活性氯化钠转运的影响。
Calcium/calmodulin is involved in the regulation of basal rabbit ileal active Na and Cl absorption, but the mechanism by which elevated intracellular Ca2+ affects Na and Cl transport is unknown. To investigate the roles of the Ca2+/calmodulin and protein kinase C systems in ileal NaCl transport, two drugs, the isoquinolenesulfonamide, H-7, and the naphthalenesulfonamide, W13, were used in concentrations that conferred specificity in the antagonism of protein kinase C (60 .mu.M H-7) and Ca2+/calmodulin (45 .mu.M W13), respectively, as determined using phosphorylation assays in ileal villus cells. W13 but not H-7 stimulated basal active NaCl absorption. H-7 inhbitied changes in Na and Cl absorption caused by maximal concentrations of Ca2+ ionophore A23187 and carbachol and serotonin, secretagogues that act by increasing cytosol Ca2+, while W13 had no effect. In contrast, neither H-7 nor W13 altered the change in NaCl transport caused by the cyclic nucleotides 8-Br-cAMP and 8-Br-cGMP. These data suggest that: (a) basal rabbit ileal NaCl absorption is regulated by the Ca2+/calmodulin complex and not by protein kinase C; (b) the effect of elevating intracellular Ca2+ to decrease NaCl absorption is mediated via protein kinase C but not by Ca2+/calmodulin; (c) the effects of protein kinase C are not overlapping or synergistic with those of Ca2+/calmodulin on either basal absorption or on the effects of increased Ca2+; and (d) neither Ca2+/calmodulin nor protein kinase C are involved in the effects of cAMP and cGMP on ileal active NaCl transport.