Luminal secretion of myo-inositol by the rat epididymis perfused in vitro

Epididymal epithelium: Its contribution to the formation of a luminal fluid microenvironment

“…Probably D-glucose is transported alone as transport was shown not to involve countertransport nor a glucose-inositol exchange system (Hinton and Howards, 1982). Inositol is also transported readily, especially across the epithelia of the initial segment and caput epididymidis (Hinton and Howards, 1982;Lewin and Sulimovici, 1975) and to a limited extent across the cauda epididymidis (Cooper, 1982;Cooper et al, 1985;Hinton and Howards, 1982). Unlike glucose, inositol is transported against a concentration gradient and presumably an active transport carrier is responsible as has been shown for other tissues (Caspary and Crane, 1970;Cotlier, 1970;Spector and Lorenzo, 1975).…”

Characteristics of the transport of carnitine into the cauda epididymidis of the rat as ascertained by luminal perfusion in vitro

“…They were then unravelled and rendered sperm-free over a period of 30-45 min, during which time they were kept in ice-cold medium. The solutions used were those described by Cooper et al (1985), except that Fraction V bovine serum albumin (BSA-V) or fatty acid-free BSA (FAF-BSA) were used, and the concentration of L-carnitine (a gift from Sigma Tau, Industrie Farmaceutiche, %unite SPA, Rome, Italy) was 60 pM in the bathing (peritubular) fluid (PTF), or altered as stated below. The length of the unravelled tubules was measured at the end of the perfusions.…”

“…The intraluminal fluid (ILF), described by Cooper et al (1985), was maintained at an osmotic pressure of 325 f 22 mOsmol/kg, by substitution of sucrose (166 mM) for choline, because choline in the lumen is known to stimulate carnitine transport in the rat epididymis (Yeung et al 1980). Intraluminal fluid was modified in active transport studies by addition of [14C]inulin (0.23 pCi/ml: 7.9…”

“…These experiments have shown that the epididymis can transport both inositol (Cooper 1982;Hinton & Howards 1982;Sujarit et al 1985) and carnitine (Yeung et al 1980;Hinton & Setchell 1980) from the circulation to its lumen against substantial concentration differences. The presence of saturable carriers for inositol, glucose and amino acids in the epididymis has been demonstrated by the reduction in transport of tracer to the lumen when the concentration of unlabelled compound is raised in the circulation (Hinton & Howards 1982), but such studies are more easily achieved in vitro using a luminal perfusion technique (Cooper et al 1985). The latter technique enables precise control of the conditions of transport and is therefore useful in the study of transport kinetics.…”

Transport of carnitine by the epididymis of the cynomolgus macaque (Macaca fascicularis)

“…Spermatozoa were flushed from the lumen with a fluid containing 13mM-NaCl, 50mM-KCl, 2-6mM-CaCl2, l-lmM-MgS04, 166mM-sucrose and 18mM-N-morpholinopropanesulphonic acid adjusted to pH 6-9 with NaOH. This solution is similar to that described by Cooper, Yeung, Lui & Yang (1985), except that sucrose (166 mM) was substituted for choline, because choline is known to stimulate carnitine secretion in the rat (Yeung et ai, 1980). After cannulation the tubules were transferred to an aerated bath fluid containing the medium in which they had been dissected (20 ml) to which had been added 1 mg bovine serum albumin/ml (Fraction V) Bands of 5 mm were scraped from the plate into scintillation vials to which 0-3 ml water and 2 ml Aqualuma Plus scintillant were added.…”