VOL. 4, No. 1, January 2008

M. N. Ghayur, et al. [2008] Med Hypotheses Res. 4: 1–9.

Contractility of the Renal Glomerulus and Mesangial
Cells: Lingering Doubts and Strategies for the Future

Muhammad N. Ghayur, Joan C. Krepinsky and Luke J. Janssen*

Department of Medicine, McMaster University, St. Joseph’s Hospital, Hamilton, L8N 4A6,
Ontario, Canada

Abstract. Kidneys can be divided into four components: glomeruli, tubules,
interstitium and blood vessels. The renal glomerulus consists of a network of capillaries
covered with epithelial cells called podocytes. The entire glomerular tuft is structurally
supported by mesangial cells which are contractile in nature and resemble vascular smooth
muscle cells. Mesangial cells are secretory, producing growth factors and matrix proteins
which have a role in both normal glomerular development and in pathologic states. They
have also been shown to take the role of macrophages. The importance of mesangial cell
contraction to glomerular physiology remains debated. It is postulated that mesangial cell
contraction can attenuate the glomerular filtration rate by decreasing the renal ultrafiltration
coefficient through a decrease in capillary surface area and capillary permeability. The
physiology of mesangial cell contraction has been studied primarily utilizing cultured cells.
The physiological status of receptors and ion channels may be doubtful, however, given the
phenotypic changes cells are known to acquire in culture conditions. The contractility of
renal glomeruli has been less well studied. In this report, we review the available data
regarding the contractility of mesangial cell and of renal glomeruli. Moreover, we suggest
newer techniques that can be used with whole glomeruli, thereby improving upon the data
collected using previous techniques and cultured cells.

* Correspondence: Dr. Luke J. Janssen, Department of Medicine, McMaster
University, St. Joseph’s Hospital, Room L-314, 50 Charlton Ave. East, Hamilton L8N 4A6,
Ontario, Canada. PHONE: 905-522-1155 (ext. 35912). FAX: 905-540-6510.

Full Text PDF