ISSN:
1432-2013
Keywords:
Isolated protoplasm
;
Nitella
;
Electrical responses
;
RC network
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Isolated protoplasmic droplets of the alga Nifella were investigated with microelectrodes under current clamp conditions. The following observations were made: 1. Long pulses of either polarity yielded almost symmetric current-voltage relations. Near the rather small resting potential (inside negative) the measuring points lay on a straight line corresponding to an apparent surface membrane resistance of 1.7±0.45 kΩ (mean ± S.E.M.,n=5). 2. Experiments with various pulse programs revealed no mechanism comparable to Na inactivation but stressed the electrical symmetry of the droplet with respect to the resting potential. 3. Changes of the [Ca2+] in the bathing medium between 0 and 10 mM as well as of the pH between 5 and 9 did not influence the responses. Replacing K+ by Na+ (or vice versa) or exchanging NO 3 − for acetylglycine or Cl− was also ineffective. These observations are not consistent with a normal excitable surface membrane. Similar responses are obtained with a RC network which is described and which may have its substrate in histological peculiarities of the protoplasmic droplet.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00587291
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