Voltage- and Agonist-Induced Activation of Smooth Muscle of the Human Upper Urinary Tract: Different Mechanisms

Abstract

Smooth muscles are such a remarkably diverse group of tissues that the difference in properties between any two of them may be as great as between a smooth muscle and a striated muscle. With this diversity it is not surprising that the ways in which different stimuli initiate contraction are also extremely varied and interesting although we still know very little about the details of the mechanisms involved. In an attempt to shed some light on the cellular contraction cycle of smooth muscle of the human upper urinary tract, this article will focus on two topics:

• 1. Previous findings in smooth muscle research will be summarized and discussed briefly as they are pertinent to an understanding of the mechanical activity of the upper urinary tract.

• 2. Experimental findings from human preparations will be demonstrated as examples for different modes of activation of smooth muscle. Based on findings from other smooth muscle tissues a concept of different activation mechanisms will be presented.