Ethan Tapper

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To determine how sulfation alters the biological properties of dihydroxy bile acids, we compared the effects of 3-sulfodeoxycholate (SDC) and deoxycholate (DC) in the rat and rabbit intestine. While 5 mM DC induced water and electrolyte secretion and inhibited glucose absorption in the rat, SDC enhanced jejunal and ileal water and solute absorption. SDC had(More)
The effect of aspirin on normal and cholera toxin-stimulated electrolyte transport has been investigated in vitro, because this drug appears to inhibit cholera toxin-induced intestinal secretion in in vivo animal models. In the Ussing chamber, 10 mM aspirin decreased the control rabbit ileal potential difference and short-circuit current by 50% and(More)
The autonomic control of intestinal electrolyte transport has been investigated in the in vitro, short-circuited rabbit ileum with varying doses of carbachol and with neuroeffector blocking agents. Low-dose carbachol (less than 10(-6) M) and high-dose carbachol (greater than 10(-4) M) had different effects on Na and Cl transport. Low-dose carbachol caused a(More)
To study the effects of endogenous norepinephrine on intestinal ion transport, we tested the actions of an indirect sympathomimetic agent, tyramine, on electrolyte fluxes in the short-circuited rabbit ileum in vitro. Tyramine (10(-5) M) alone had no effect on short-circuit current or Na transport but increased Cl absorption. Tyramine decreased the(More)
Studies of stand dynamics can explain how species interactions and disturbances drive forest structure and recruitment patterns of tree species. It is difficult to generate an understanding of stand dynamics and successional trends of forests in areas that have a long history of intense land use such as the Champlain Valley of Vermont, where over 230 years(More)
Principles of autonomic nervous system control of intestinal ion transport need to include the newer concepts of the enteric nervous system (ENS). Based on studies of nervous control of the myenteric plexus, it is likely that ENS control of intestinal transport occurs through local mechanisms. In vitro transport studies and a limited number of(More)