Silva P, Epstein F H
Mount Desert Island Biological Laboratory, Salsbury Cove, Maine, MA 04670, USA.
J Comp Physiol B. 2002 Dec;172(8):719-23. doi: 10.1007/s00360-002-0302-z. Epub 2002 Oct 16.
The salt gland of the spiny dogfish, Squalus acanthias, can be stimulated to secrete chloride by two different endogenous peptides: cardiac natriuretic peptide (CNP) and the neurotransmitter, vasoactive intestinal peptide (VIP). We examined the role of the actin cytoskeleton and of myosin light chains in this process by perfusing isolated rectal glands with and without an inhibitor of actin filament organization (cytochalasin D) and an inhibitor of myosin light chain kinase (ML-7). Cytochalasin D, 10(-6) M, reduced secretion stimulated by a 1-min bolus of CNP (5x10(-7) M) by 50-60%. In the presence of 10(-2) M procaine (which blocks neural release of VIP), cytochalasin D completely prevented CNP stimulation. In contrast, cytochalasin D did not inhibit stimulation of the rectal gland by VIP or by forskolin. Similarly, 5x10(-6)M ML-7 almost completely inhibited direct stimulation of rectal gland secretion by CNP, but did not alter chloride secretion induced by VIP or forskolin. Finally, the average time between hormonal injection and activation of secretion was 2 min longer for CNP than for VIP, consistent with the hypothesis that a contractile cellular function involving the cytoskeleton is important in CNP-induced chloride secretion, but less so when secretion is stimulated by VIP.
棘鲨（Squalus acanthias）的盐腺可被两种不同的内源性肽刺激分泌氯化物：心钠素（CNP）和神经递质血管活性肠肽（VIP）。我们通过用肌动蛋白丝组织抑制剂（细胞松弛素D）和肌球蛋白轻链激酶抑制剂（ML-7）灌注分离的直肠腺，研究了肌动蛋白细胞骨架和肌球蛋白轻链在此过程中的作用。10^(-6) M的细胞松弛素D使由1分钟推注的CNP（5×10^(-7) M）刺激的分泌减少了50%-60%。在存在10^(-2) M普鲁卡因（其阻断VIP的神经释放）的情况下，细胞松弛素D完全阻止了CNP的刺激。相比之下，细胞松弛素D并不抑制VIP或福斯高林对直肠腺的刺激。同样，5×10^(-6) M的ML-7几乎完全抑制了CNP对直肠腺分泌的直接刺激，但并未改变VIP或福斯高林诱导的氯化物分泌。最后，激素注射与分泌激活之间的平均时间，CNP比VIP长2分钟，这与以下假设一致：涉及细胞骨架的收缩性细胞功能在CNP诱导的氯化物分泌中很重要，但在VIP刺激分泌时则不太重要。
