Inhibition of Maize (Zea mays L.) Root Plasma Membrane-Bound Redox Activities by Coumarins

1994 ◽  
Vol 49 (7-8) ◽  
pp. 447-452 ◽  
Author(s):  
Sabine Lüthje ◽  
José A. Gonzaléz-Reyes ◽  
Placido Navas ◽  
Olaf Döring ◽  
Michael Böttger
Keyword(s):  
Zea Mays ◽  
Plasma Membrane ◽  
Zea Mays L ◽  
Membrane Vesicles ◽  
Dependent Manner ◽  
Plasma Membrane Vesicles ◽  
Two Phase ◽  
Concentration Dependent Manner ◽  
Oxidoreductase Activity ◽  
Membrane Bound

Modulation of plasma membrane-bound NADH:hexacyanoferrate III oxidoreductase activities by dicumarol and warfarin was investigated with plasma membrane vesicles of Zea mays L. (cv. Sil Anjou 18) roots, prepared by aqueous two phase partitioning. Vesicles were about 65% right-side out orientated as demonstrated by enzyme latency of vanadate sensitive ATPase activity. Dicumarol or warfarin, respectively, inhibited NADH:hexacyanoferrate III oxidoreductase activity in a concentration-dependent manner and inhibition could be reversed partially by addition of quinones

Inhibition of Na+/Ca2+ exchange in renal BLMV by IP3 depends on site of action and direction of Ca2+ flux

1994 ◽  
Vol 266 (5) ◽  
pp. F785-F790 ◽  
Author(s):  
C. L. Fraser ◽  
C. Cummings ◽  
G. Cassafer
Keyword(s):  
Plasma Membrane ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Dependent Manner ◽  
The Novel ◽  
Concentration Dependent Manner ◽  
Site Of Action ◽  
Brain Synaptosomes ◽  
Membrane Bound ◽  
Inside Out

It has previously been shown in synaptosomes that inositol 1,4,5-trisphosphate (1,4,5-IP3) inhibits Ca2+ transport by the plasma membrane-bound Na+/Ca2+ exchanger. The present study was therefore designed to determine if the effect of 1,4,5-IP3 was dependent on its site of action at the plasma membrane or on the direction of Ca2+ flux. To investigate this possibility, studies were performed in basolateral membrane vesicles (BLMV) isolated from rat renal cortex. As with synaptosomes, Ca2+ transport was inhibited by 1,4,5-IP3 in a concentration-dependent manner. At a concentration of 10(-6) M, 1,4,5-IP3 significantly (P < 0.005) inhibited Ca2+ transport by 36%. When Ca2+ transport was carried out in inside-out vesicles, 10(-6) M 1,4,5-IP3 significantly (P < 0.002) increased the degree of inhibition by an additional 75% (63 vs. 36%). However, 1,4,5-IP3 had no significant effect on Ca2+ transport in inside-out vesicles when Ca2+ flux was reversed (i.e., Ca2+ efflux). These data in renal BLMV confirm the novel action of 1,4,5-IP3 on the Na+/Ca2+ exchanger previously described in brain synaptosomes. These results also suggest that the action of 1,4,5-IP3 depends on both its site of action at the plasma membrane and on the direction of Ca2+ flux.

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