It’s been 40 years since I attended the Biophysical Society Annual Meeting in San Francisco (February 9–13, 1986), coauthoring a poster about earthworms. The lead author was Frans Gielen, a post doc working in John Wikswo’s laboratory at Vanderbilt University when I was a graduate student there. The last author was Peter Brink, a friend of Wikswo’s and an expert on electrical synapses, particularly in an earthworm axon.
Wikswo and I had been performing experiments on crayfish axons, which are long, straight, and uninterrupted along their length (I’ve written about these experiments before in this blog). We used a wire-wound, ferrite-core toroid to measure the action current along the axon, and compared it to the action potential measured simultaneously with a microelectrode. The interesting thing about the earthworm is that their medial giant axon is divided into segments by septa, which are low resistance electrical synapses also known as gap junctions. At the University of Illinois Brink had studied septa with Lloyd Barr, one of the first researchers to make electrical measurements on a septum (“The Resistance of the Septum of the Median Giant Axon of the Earthworm,” Journal of General Physiology, Volume 69, Pages 517–536, 1977). Our goal was to see if the gap junctions had high enough resistance to reduce the axial action current at the site of a septum.
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| Using a toroid to measure the action current in a nerve axon. |
According to my research notebooks, Brink visited Vanderbilt twice in 1985 for these experiments: first on April 18 and again on July 30. He taught us the dissection—which was easier than the crayfish dissections I had been doing, because the earthworm nerve is robust and not damaged by stretching—and brought the Lucifer Yellow dye needed to visualize the septum. We scanned the toroid along the axon looking for a change in current near the septum. Looking back at the data, it was pretty noisy and inconclusive. But the initial results were enough for a meeting abstract, and we submitted the data to the Biophysical Society meeting.
I enjoyed working with Brink, who was about Wikswo’s age, meaning he was several years older than me but still a young professor, fun-loving and irreverent. He went on to a long career at the State University of New York at Stony Brook, rising to become chair of the Department of Physiology and Biophysics. Throughout his career he did a lot of highly cited work on gap junctions, particularly in cardiac tissue.
Below is our abstract to the Biophysical Society Meeting. We never obtained enough good data to write a full research article, so this abstract is my only contribution to earthworm physiology. What I remember most about the meeting was riding a cable car, walking out onto the Golden Gate Bridge, and eating lobster at Fisherman’s Wharf.
