Electrical coupling between smooth muscle and endothelium in arterioles of the guinea-pig small intestine.

Equations describing the steady-state passive electrical properties of arterioles have been derived. The arteriole was modelled as having two thin layers of cells (muscle and endothelium) with strong electrical coupling between cells within a layer and variable coupling between the layers. The model indicated that spread of membrane potential changes was highly dependent on the thickness of cells within the layers. The model was also used to identify the optimal experimental strategy for detecting coupling between the two layers, and experiments were carried out on arterioles from the guinea-pig small intestine. Thickness of the endothelial layer was measured using electron microscopy and was found to be around 0.5 microm. Electrical input resistance was measured in intact arterioles and compared to input resistance of arterioles from which the endothelium had been removed. The experiments confirmed that there was a strong electrical coupling between the muscle and endothelium in these vessels.