Angiotensin II and connective tissue: homeostasis and reciprocal regulation

As a concept traditionally applied to integrative organ physiology, homeost asis likewise applies to self-regulated growth and structure of loose, dens e and specialized connective tissues. De novo generation and co-induction o f signals, either stimulatory or inhibitory to the formation of these tissu es, provide for a reciprocal regulation of their composition; angiotensin ( Ang) II is a growth stimulator. Components involved in AngII generation and its biological activity, including angiotensin converting enzyme (ACE) and AngII receptors, are expressed by mesenchymal cells responsible for connec tive tissue turnover. ACE inhibition or AT1 receptor antagonism attenuate t he formation of these connective tissues. The concept of circulatory homeos tasis, and the endocrine properties of plasma AngII involved in maintaining same, need each be broadened to encompass auto- and paracrine effects of A ngII produced within connective tissues, where it contributes to their home ostatic regulation of structure and composition. (C) 1999 Elsevier Science B.V. All rights reserved.