The first type of experiment involves membranes containing 2 sodium channels modified by addition of batrachotoxin. We found that the probabilities that 0, 1, or 2 of these channels are open do not follow a binomial distribution, indicating that the channels are not independent, are not identical, or both. To distinguish among these possibilities, we assumed that the channels are independent, and tried to determine whether this assumption is consistent with all our data. We found that the assumption is not consistent with the open probabilities for 1-channel membranes, and therefore that the assumption is incorrect; the channels must be dependent. We further showed that the type of dependence is anti-cooperative; i.e. the opening of one channel reduces the probability that the other channel will be open. Another type of experiment involves channels in the cells of the plant samanea saman. We performed patch clamp experiments to determine that these cells do indeed contain channels and to identify the type of channel. We found evidence for potassium channels, suggesting a mechanism for the opening or closing of the leaflets of the plant in light or dark, respectively. Our data are consistent with the view that light opens potassium channels in cells in the extensor region of the pulvinus, and that this results in an influx of potassium together with anions and water, causing the extensor to swell and the leaflets to open.
