Sodium and glucose transport across the in vitro perfused midgut of the blue crab, Callinectes sapidus Rathbun

Transepitheliald-glucose andd-fructose transport across the American lobster,Homarus americanus, intestine

“…The presence of an SGLT1-like glucose transporter on the mucosal membrane of the lobster intestine, as shown by the inhibition of glucose transport in the presence of phloridizin (Fig.3A), has previously been reported in mammals (Drozodowski and Thomson, 2006;Helliwell and Kellett, 2002;Turk et al, 1994;Turk and Wright, 1997), parasitic wasp larvae (Caccia et al, 2007), blue crabs (Chu, 1986), freshwater prawns (Ahearn and Maginniss, 1977) and a variety of other vertebrates and invertebrates. Although mammalian and crustacean intestines appear to have similar mucosal glucose and fructose transporters, SGLT1 and GLUT5 respectively, the kinetic constants for these transporters in these organisms differ.…”

“…Although mammalian and crustacean intestines appear to have similar mucosal glucose and fructose transporters, SGLT1 and GLUT5 respectively, the kinetic constants for these transporters in these organisms differ. In mammals, the apparent binding affinity, K m , of both intestinal glucose and fructose transport was reported to be in the millimolar range (Kellett, 2001;Au et al, 2002), while in lobster, prawn and crab intestines the K m values of these sugars are in the micromolar range ( Fig.1A and Fig.2A) (Ahearn and Maginniss, 1977;Chu, 1986). In contrast, sugar transport K m values in crustacean hepatopancreatic epithelial cells are much higher than those in the intestine of the same species, and even approximate those reported I. E. Obi, K. M. Sterling and G. A. Ahearn for the mammalian digestive tract (Ahearn et al, 1985;Verri et al, 2001).…”

“…In crustaceans, the hepatopancreas and the intestine play a role in the absorption of dietary glucose (Ahearn et al, 1985;Verri et al, 2001), with the hepatopancreas being the major site of sugar absorption (Ahearn and Maginniss, 1977;Chu, 1986;Sterling et al, 2009). The crustacean hepatopancreas is a large, bilateral organ that is composed of five different cell types: E, F, R, B and M cells (Verri et al, 2001).…”

3H-l-histidine and 65Zn2+ are cotransported by a dipeptide transport system in intestine of lobsterHomarus americanus

“…This solution was also perfused through the intestines as the mucosal medium using a peristaltic pump (Instech Laboratories, Inc., Plymouth Meeting, PA, USA) at a flow rate of 380·µl·min -1 for periods of time up to 180·min. Previous studies using other crustacean species have shown intestinal viability under the conditions used in the present work for up to 5·h of continuous perfusion (Ahearn and Hadley, 1977a,b;Ahearn and Maginniss, 1977;Chu, 1986). Variable concentrations of L-histidine, Zn 2+ or glycyl-sarcosine were added to the mucosal medium as needed.…”

“…In vitro transmural transports of L-histidine, Zn 2+ and glycylsarcosine were examined using a simple perfusion apparatus as described in detail previously (Ahearn and Hadley, 1977a,b;Ahearn and Maginniss, 1977;Brick and Ahearn, 1978;Wyban et al, 1980;Chu, 1986). Briefly, intact intestines were flushed of contents and mounted with surgical thread on blunted 18-20 gauge stainless steel needles in a lucite chamber containing the incubation medium (10·ml), which served as the serosal medium.…”