scholarly journals EFFECTS OF CADMIUM ON THE ACTIVE TRANSPORT OF SODIUM BY THE ABDOMINAL SKIN OF A BULLFROG (RANA CATESBEIANA)

1977 ◽  
Vol 27 (3) ◽  
pp. 337-352 ◽  
Author(s):  
Hideo HAYASHI ◽  
Makoto TAKADA ◽  
Akira ARITA
Keyword(s):  
Active Transport ◽  
Rana Catesbeiana ◽  
Abdominal Skin

On the structural organization of biological pumps and channels

1984 ◽  
Vol 42 ◽  
pp. 138-141
Author(s):  
G. Zampighi ◽  
M. Kreman
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Plasma Membranes ◽  
Transport Proteins ◽  
Molecular Organization ◽  
Passive Transport ◽  
Concentration Gradients ◽  
Cell Functions ◽  
Natural Concentration ◽  
Active Transport System

The plasma membranes of most animal cells contain transport proteins which function to provide passageways for the transported species across essentially impermeable lipid bilayers. The channel is a passive transport system which allows the movement of ions and low molecular weight molecules along their concentration gradients. The pump is an active transport system and can translocate cations against their natural concentration gradients. The actions and interplay of these two kinds of transport proteins control crucial cell functions such as active transport, excitability and cell communication. In this paper, we will describe and compare several features of the molecular organization of pumps and channels. As an example of an active transport system, we will discuss the structure of the sodium and potassium ion-activated triphosphatase [(Na+ +K+)-ATPase] and as an example of a passive transport system, the communicating channel of gap junctions and lens junctions.

Vesicular system associated with spermiogenesis of bullfrog

1987 ◽  
Vol 45 ◽  
pp. 818-819
Author(s):  
K. C. Liu ◽  
S. F. Tsay
Keyword(s):  
Electron Microscopy ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Reproductive System ◽  
Seminiferous Tubule ◽  
Rana Catesbeiana ◽  
Routine Procedure ◽  
Electron Microscopic ◽  
Twisted Tubules ◽  
Electron Lucent

In the histologic and electron microscopic study of the male reproductive system of bullfrog, Rana catesbeiana, a vesicular system associated with spermiogenesis was observed. It appeared in the lumenal space of the seminiferous tubule (Fig. 1), in the heads of spermatids (Fig. 2), associated with the chromatins of the spermatid (Fig. 4). As deduced from sections, this vesicular system consisted of vesicles of various size or a large group of waving and twisted tubules (Fig. 3), After routine procedure of treatment for electron microscopy, the lumens of both of the vesicles and tubules were electron lucent.In human, vesicles and vesicular system associated with reproductive cell and tissue were reported. In abnormal spermiogenesis, flower-like body, actually vesicles, and giant vesicle associated with the head of spermatid were observed. In both cases the number of vesicle was limited from a single one to a few.

Pneumatically-driven Microfluidic Device for Evaluating Active Transport by Kinesin Motor Protein

2016 ◽  
Vol 136 (9) ◽  
pp. 384-389
Author(s):  
Kazuya Fujimoto ◽  
Hirofumi Shintaku ◽  
Hidetoshi Kotera ◽  
Ryuji Yokokawa
Keyword(s):  
Active Transport ◽  
Microfluidic Device ◽  
Motor Protein ◽  
Kinesin Motor

Chloride secretion and conductance of teleost opercular membrane: effects of prolactin

1982 ◽  
Vol 242 (3) ◽  
pp. R380-R389 ◽  
Author(s):  
J. K. Foskett ◽  
T. E. Machen ◽  
H. A. Bern
Keyword(s):  
Active Transport ◽  
Short Circuit ◽  
Chloride Secretion ◽  
Alternative Interpretation ◽  
Chloride Cells ◽  
Dependent Manner ◽  
Transport Pathway ◽  
Accurate Analysis ◽  
Equivalent Circuit Analysis ◽  
Fish Yield

Effects of prolactin on transport properties of opercular membranes from seawater-adapted tilapia, Sarotherodon mossambicus, have been examined. These membranes are high conductance (average Gt approximately 4 mS.cm-2) tissues with short-circuit currents (I) equal to net chloride secretion. Despite high Gt, nonlinear current-voltage relationships suggest that opercular membranes cannot be classified as "leaky" tissues. Variability among membranes is reflected in a linear relationship between I and Gt with a slope equal to 26 mV and the zero-current Gt intercept equal to 0.45 mS.cm-2. Prolactin injections decrease I and Gt in a dose-dependent manner. Phosphodiesterase inhibition, without effect on I in untreated fish, often partially reverses these prolactin effects. Gt-I data from prolactin-treated fish yield a slope of 18 mV and a Gt intercept of 0.10 mS.cm-2. The effects of prolactin are discussed in terms of conventional equivalent circuit analysis. Discrepancies between predictions based on this model and the actual data indicate that an alternative interpretation, based on a heterogeneous cell population, is more accurate. Analysis of this circuit suggests that the ratio of paracellular to active transport pathway conductances associated with chloride cells is constant and that differences in Gt and I are due to parallel changes in these conductances. Prolactin may effectively "remove" chloride cells from these membranes as well as inhibit (reversible by elevated cellular cAMP levels) active transport pathway conductance of remaining cells.

Carrier-Mediated Active Transport of a Novel Thromboxane A2 Receptor Antagonist [2-(4-Chlorophenylsulfonylaminomethyl)indan-5-yl]acetate (Z-335) into Rat Liver

2002 ◽  
Vol 30 (5) ◽  
pp. 498-504 ◽  
Author(s):  
Yoshihiro Kawabata ◽  
Shigeru Furuta ◽  
Yutaka Shinozaki ◽  
Tadashi Kurimoto ◽  
Ryuichiro Nishigaki
Keyword(s):  
Receptor Antagonist ◽  
Active Transport ◽  
Rat Liver ◽  
Thromboxane A2 ◽  
Thromboxane A2 Receptor
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