Action Of Heptaminol Hydrochloride On Contractile Properties In Frog Isolated Twitch Muscle Fibre, Bruno Allard, Vincent Jacquemont, Fouad Lemtiri-Chlieh, Bernard Pourrias, Oger Rougier
Jul 1991
Action Of Heptaminol Hydrochloride On Contractile Properties In Frog Isolated Twitch Muscle Fibre, Bruno Allard, Vincent Jacquemont, Fouad Lemtiri-Chlieh, Bernard Pourrias, Oger Rougier
fouad Lemtiri-Chlieh
1 Heptaminol stopped or delayed the progressive decline in tension which characterizes the phenomenon of fatigue in frog isolated twitch muscle fibre.
2 Heptaminol had no action on the sodium, potassium and calcium voltage-dependent ionic conductances.
3 The hypothesis of an action via an internal alkalinization was tested by comparison with the action of NH4Cl. Both substances increased the tension.
4 The action of hepataminol was suppressed in sodium-free (TRIS) solution or in the presence of amiloride while the action of NH4Cl was always observed.
5 These results could be explained by a stimulation of the Na/H antiport by heptaminol.
The Electrical Response Of Maize To Auxin, Hubert Felle, Winfried Peters, Klaus Palme
May 1991
The Electrical Response Of Maize To Auxin, Hubert Felle, Winfried Peters, Klaus Palme
Winfried S. Peters
The electrical response of Zea mays coleoptiles and suspension cultured cells to several growth-promoting auxins (IAA, IBA, 2,4-D, 2,4,5-T, 1-NAA) and some of their structural analogues (2,3-D, 2-NAA) has been tested. In coleoptiles two typical electrical responses to IAA are observed: an immediate rapid depolarization, and a hyperpolarization following 7–10 minutes after the first external addition of IAA. Of the other tested compounds only 1-NAA significantly depolarized the cells, whereas all auxins as well as the analogues evoked delayed hyperpolarizations. In contrast, the suspension cells were not hyperpolarized by any of the tested compounds, but were strongly depolarized by IAA, …
Control Of Apoplast Ph In Corn Coleoptile Segments. I: The Endogenous Regulation Of Cell Wall Ph, Winfried Peters, Hubert Felle
Apr 1991
Control Of Apoplast Ph In Corn Coleoptile Segments. I: The Endogenous Regulation Of Cell Wall Ph, Winfried Peters, Hubert Felle
Winfried S. Peters
The endogenous control of cell wall pH of Zea mays L. coleoptiles has been investigated using abraded as well as non-abraded segments. Regardless of the initial medium pH, coleoptile segments characteristically change the external pH: after about 2 h a pH maximum (neutral peak; NP) around 6 is reached, followed by a slow pH decrease that levels off in a steady state at 4.8 after 7 h (acid equilibrium; AE). This basic behavior is independent of medium composition, but critically requires O2; it is not altered when the number of coleoptiles per volume is increased to over 10 col./mL. Thus, …
Control Of Apoplast Ph In Corn Coleoptile Segments. Ii: The Effects Of Various Auxins And Auxin Analogues, Winfried Peters, Hubert Felle
Mar 1991
Control Of Apoplast Ph In Corn Coleoptile Segments. Ii: The Effects Of Various Auxins And Auxin Analogues, Winfried Peters, Hubert Felle
Winfried S. Peters
Using abraded Zea mays L. coleoptile segments, proton extrusion has been measured in the presence of growth promoting auxins and their inactive structural analogues. Prior to application, the segments spontaneously acidified the external medium to pH 4.8 within 7 h. Indole-3-acetic acid (IAA) concentration dependently decreases external pH to 4.2, fusicoccin (FC) to below 3.5. Whereas the IAA-effect spontaneously recovers and can be repeated, the FC-effect is final and irreversible. The growth promoting auxins 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), indole-3-butyric acid (IBA) and 1-naphthylacetic acid (1-NAA) all stimulate proton extrusion similar to IAA. The growth inactive structural analogues 2,3-dichlorophenoxyacetic …
