Reporting Live from Mount Desert Island Biological Laboratories

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I’m coming to you live for the next week from Mount Desert Island Biological Lab (MDIBL) in Maine, where I’m taking a course entitled “Origins of Renal Physiology.

The course is designed for renal fellows such as myself who seek to establish a career in nephrology research and to discuss the foundations upon which our understanding of renal physiology is based by repeating and expanding upon many of these classic experiments. MDIBL is a small, private lab whose focus is on the physiology of marine animals, many of whom were the model systems for determining such basic phenomena as salt and water homeostasis and how ions are secreted and reabsorbed.

As an example, tomorrow we will do some work on the shark rectal gland. Here is a picture of one of the shark tank at MDIBL:
And here is a picture of what the shark rectal gland looks like:

Why study the shark rectal gland at a kidney course? The shark lives in salt water, where the NaCl concentration is about 600mM, yet their plasma NaCl concentration is only about 200mM. The shark has evolved a mechanism to tolerate such a hyperosmolar environment: its rectal gland, which secretes a massive amount of Na+ and Cl- to maintain its osmolarity. The concentrations of both the Na-K ATPase and the Na-K-2Cl (a.k.a. the “loop Na channel”) are exceptionally high in this tissue and therefore these enzymes were initially purified with shark rectal gland as a source, so it has already played an important role in our understanding of renal Na+ and Cl- handling.

I’ll be posting more about the experiments we do and the renal lessons I’ve learned as time allows…

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