Dartt D A, Baker A K, Rose P E, Murphy S A, Ronco L V, Unser M F
Immunology Unit, Eye Research Institute, Boston, MA 02114.
Invest Ophthalmol Vis Sci. 1988 Nov;29(11):1732-8.
Addition of a cholinergic agonist carbachol and vasoactive intestinal peptide (VIP) to dispersed rat exorbital lacrimal gland acini produces protein secretion, measured by secretion of the enzyme peroxidase, that was statistically significantly greater than additive (potentiated). To determine where in stimulus-secretion coupling these secretagogues interact to potentiate secretion, rat exorbital gland acini were incubated simultaneously with cyclic AMP- and Ca2+-dependent agonists and protein secretion, cyclic AMP level, or Ca2+ concentration measured. As a measure of protein secretion, the supernatant obtained after centrifugation of acini was analyzed for peroxidase, a protein secreted by rat lacrimal glands. Interaction did not occur at the receptor level, because peroxidase secretion also was potentiated by simultaneous addition of carbachol and forskolin, which activates the catalytic subunit of adenyl cyclase. A potentiated increase in the cyclic AMP level did not potentiate protein secretion, because the level was the same with VIP as with carbachol and VIP added together at concentrations that potentiated peroxidase secretion. A potentiated increase in free intracellular [Ca2+] did not potentiate protein secretion, because [Ca2+] was greater with carbachol than with carbachol and VIP added together at concentrations that potentiated peroxidase secretion. We conclude that cholinergic- and VIP-dependent pathways interact to potentiate lacrimal gland protein secretion after the rise of intracellular cyclic AMP or Ca2+.
向分散的大鼠眶外泪腺腺泡中添加胆碱能激动剂卡巴胆碱和血管活性肠肽（VIP），可产生蛋白质分泌，通过酶过氧化物酶的分泌来衡量，其分泌量在统计学上显著高于两者单独作用之和（增强作用）。为了确定这些促分泌剂在刺激-分泌偶联过程中的相互作用位置以增强分泌，将大鼠眶外腺腺泡与依赖环磷酸腺苷（cAMP）和钙离子（Ca2+）的激动剂同时孵育，并测量蛋白质分泌、cAMP水平或Ca2+浓度。作为蛋白质分泌的衡量指标，对腺泡离心后获得的上清液进行过氧化物酶分析，过氧化物酶是大鼠泪腺分泌的一种蛋白质。在受体水平未发生相互作用，因为同时添加卡巴胆碱和激活腺苷酸环化酶催化亚基的福斯高林也能增强过氧化物酶的分泌。cAMP水平的增强升高并未增强蛋白质分泌，因为在增强过氧化物酶分泌的浓度下，单独添加VIP时的cAMP水平与同时添加卡巴胆碱和VIP时相同。细胞内游离Ca2+的增强升高并未增强蛋白质分泌，因为在增强过氧化物酶分泌的浓度下，单独添加卡巴胆碱时的Ca2+浓度高于同时添加卡巴胆碱和VIP时的Ca2+浓度。我们得出结论，胆碱能和VIP依赖的途径在细胞内cAMP或Ca2+升高后相互作用，以增强泪腺蛋白质分泌。
