V a s c u l a r   B i o l o g y

The vascular biology division pioneered the characterization of contractility and Ca²⁺ signaling pathways in smooth muscle tissues from mice. Our data bank includes: aorta, portal vein, mesenteric arterioles, trachea, bladder, intestinal and uterine smooth muscle. Over 50 different gene-altered mice have been characterized to date.

F u n c t i o n a l   G e n o m i c s

Ca²⁺-Homeostasis:
We use gene-altered mice to understand the roles of pumps in the regulation of intracellular calcium. We have utilized gene-ablated mice and developed transgenic mice using smooth muscle specific promoters.

Smooth Muscle Motor Protein Function:
We investigate the role of isoforms Molecular motor proteins and specific contractile properties of smooth muscle.

Compartmentation, Energetics and Metabolism:
The use of continuous measurements of oxygen consumption to monitor contractile ATP requirements under controlled mechanical conditions was developed in my laboratory and downsized to take advantage of gene-altered mice models. This is of special interest in terms of compartmentation of NKA isoforms and their link to aerobic glycolysis.

M e c h a n i s m s   o f   V a s c u l a r  O x y g e n - S e n s i n g

The relaxation of systemic arteries to hypoxia is a vital protective response, leading to increased tissue perfusion. Most of the current theories invoke mechanisms that lower [Ca²⁺]_i . We have shown that in addition, there is an additional pathway that rather than leading to a decrease in [Ca²⁺]_i , this hypoxic mechanism operates through Ca²⁺ desensitization. We have used organ culture and proteomics to unravel these novel O₂ sensing pathways. Hypoxic relaxation is lost during organ culture and MALDI and TOF mass spectrometry used to identify target proteins. This enabled us to show that Rho Kinase was a key player in this Ca²⁺-desensitizing hypoxic relaxation. We continue to search for the oxygen-sensor & are expanding into studies on human cerebral and coronary vessels.

N o n - M u s c l e   C o n t r a c t i l i t y

3T3 fibroblasts cultured in collagen form a 3 dimensional gel, then shrink to form a fiber. Quantitative measurements of mechanical properties of this reconstituted fiber can be studied using the sophisticated mechanical analysis developed for muscle. Measurements of [Ca²⁺]_i on these preparation so that [Ca²⁺]_i can be correlated with mechanics and used to investigate the underlying signaling relations. Our recent studies suggest that “tensegrity” theory likely do not apply to fibroblasts and the Rho-kinase plays a major role in signaling, but not through the myosin regulatory light chain.