The inhibitory effects of prostaglandin E1 on guinea-pig ureter.

Prostaglandin E1 (PGE1) hyperpolarized the smooth muscle cells of guinea-pig ureter in normal Krebs solution and was without effect on ureters depolarized in KCl Krebs, PGE1 inhibited both electrically induced contractions and K+-induced contractures of the ureters. Conditions that favored greater tension development by the ureters, namely, high [K+] or high [Ca-2+] reduced the inhibitory effects of PGE1 on the K+-induced contractures. Depolarization of guinea-pig ureter with KCl Krebs led to an increase in radio-calcium content of the tissue over a 30 min loading period. This increase in the tissue's radio-calcium content was further increased by PGE1 but not by theophylline, PGE1 was found to have no effect on either total calcium content or the calcium efflux from the tissue. It is suggested that PGE1 exerts its inhibitory action by increasing calcium sequestration at the inner surface of the cell membrane.     

Cytochrome b mutations in Leber hereditary optic neuropathy.

New mutations were discovered in the apocytochrome b gene in Leber hereditary optic neuropathy probands who did not harbor either of the two known Complex I mutations (positions 3,460 and 11,778). A mutation at position 15,257 was found in eight independent probands which changed a highly conserved aspartate to asparagine, was not found in controls, and appears to be pathogenetically significant. The 15,257 mutation occurred in association with a known synergistic mutation at position 13,708 in 7/8 probands and in association with a new apocytochrome b mutation at position 15,812 in 4/8 probands. Mutations in Complex III genes may be involved in Leber hereditary optic neuropathy and multiple, simultaneous mutations occur frequently.     

Effect of ovulation on the ionic and water content of rabbit oviduct

The water content, extracellular space, intracellular water, potassium, sodium and chloride content of oviduct and uterus removed from rabbits in estrus and 24 and 72 h following hCG injection have been determined. Following ovulation, there was an increase in water content of the region of the oviduct corresponding to the ampullary -isthmic junction which, at 24 h, is probably due to increased intracellular water. In the ampullary-isthmic junction, ovulation decreases the potassium content and, at 24 h in the isthmic region of the oviduct, chloride is reduced. The water and ionic content of mucosa and smooth muscle cells has been calculated and mucosa cells have greater intracellular water and chloride and sodium content and less potassium and extracellular space than the smooth muscle cells of the oviduct. The significance of the changes in ionic and water content is discussed.     

A comparative assessment of methods of individual tracking within a population of Microtus agrestis (Mammalia: Muridae)

Studies of spatial arrangement in small mammal populations are usually based on the results of live-trapping, which is recognized as limiting in an investigation of this sort. The present paper examines the feasibility of two alternative methods using a population of Microtus agrestis as the test case.