Squalus acanthias

The physiological role of the ICOR is not clear and may be heterogeneous in the various tissues. In the thick ascending limb of the loop of Henle this channel appears to serve as the exit for CP at the basal cell pole [16,65,66], This conductive mechanism, therefore, is required for the reabsorption of Na and CP by this segment of the nephron [16]. In the rectal gland of Squalus acanthias a very similar channel is utilized for Na" and CP secretion. In these latter cells the CP-channel is present in the luminal membrane and is controlled by cytosolic cAMP [15,56,71]. It has been claimed that this kind of channel is also responsible for the secretion of CP in the colonic crypt cell, in colonic carcinoma cells and in respiratory epithelial cells [17,19,20,22]. Recent data have cast some doubt on this concept ... 

CP-channels with smaller conductance have first been noted in the rectal gland of Squalus acanthias by ourselves and in the colonic carcinoma cell line HT29 [61,73]. Later these types of 5-15 pS CP-channels were also found in pancreatic ducts, A6-cells and many other cells [74,75]. It is now claimed that this kind of channel is much more relevant than the ICOR for the pathophysiology of cystic fibrosis [12]. 

I have noted that NPPB is structurally related to loop diuretics of the furosemide (Fig. 2) type. These latter compounds bind to the Na 2CNK -cotransporter [16] and inhibit NaCl reabsorption in the TAL segment and NaCl secretion in epithelia such as the colonic crypt cell and rectal gland of Squalus acanthias [15]. We were able to show that only minor modification of the NPPB molecule on one side and of furosemide on the other led to compounds with altered selectivities [70,91-93]. One prototype of an intermediate blocker, i.e., a substance blocking both Na 2Cl K -cotransport and CP-channels, is torasemide (Fig. 2). Hence we have performed a systematic study in order to define the constraints defining the effectiveness of this class of substances [91]. 

Silva, P., F.H. Epstein, and R.J. Solomon. 1992. The effect of mercury on chloride secretion in the shark (,Squalus acanthias) rectal gland. Comp. Biochem. Physiol. 103C 569-575. 

Evans, D.H. and J.S. Walton. 1990. Muscarinic receptors are not involved in the nickel-induced constriction of vascular smooth muscle of the dogfish shark (Squalus acanthias) ventral aorta. Bull. Mount Desert Island Biol. Lab. 29 122-123. 

Trodusquemine (221) (isolated from the liver of the dogfish shark, Squalus acanthias) Sulfated aminosterol Trodusquemine (MSI-1436) (221) Diabetes Suppresses mammalian appetite through inhibition of protein tyrosine phosphatase IB (PTP-IB) Phase I (against type 2 diabetes and related symptoms) Genaera Corporation 974-978... 

Rao MN, Shinnar AE, Noecker LA, Chao TL, Feibush B, Snyder B, Sharkansky I, Sarkahian A, Zhang X, Jones SR, Kinney WA, Zasloff M. (2000) Aminosterols from the dogfish shark squalus acanthias. J Nat Prod 63 631-635. 

Anticancer squalamine and derivs/steroidal alkal. OSOjH marine Squalus acanthias L., Ch[Pg.163]

Malins, D.C. and Barone, A. (1970). Glyceryl ether metabolism regulation of buoyancy in dogfish Squalus acanthias. Science, New York 67,79-80. 

Sargent, J.R., Gatten, R.R. and McIntosh, R. (1971). Metabolic relationships between fatty alcohol and fatty acids in tbe liver of Squalus acanthias. Marine Biology 10, 346-355. 

Buellesbach EE, Gowan LK, Schwabe C et al. Isolation, purification, and the sequence of relaxin from spiny dogfish (Squalus acanthias). Eur J Biochem 1986 161 335. 

Diniz, M. F., and Martin, A. M. 1997. Optimization of nitrogen recovery in the enzymatic hydrolysis of dogfish (Squalus acanthias) protein. Composition of the hydrolysates. Ini. J. Food Sci. Nutri., 48,191-200. 

Betka, M., A. Welenc, D.G. Franks, M.E. Hahn and G.V. Callard. Characterization of two aryl hydrocarbon receptor (AhR) mRNA forms in Squalus acanthias and stage-specific expression during spermatogenesis. Bull. Mt Desert Isl. Biol. Lab. 39 110-112, 2000. 

Barry, T., P. Thomas and G. Callard. Stage-related production of 21-hydroxylated progestins by the dogfish (,Squalus acanthias) testis. J. Exp. Zool. 265 522-532, 1993. 

O Q Bilirubin Dogfish shark, Squalus acanthias Bile 32... 

C. Steroidal amine from the Dogfish Shark Squalus acanthias. 249... 

---