Molecular Physiology and Biophysics

Dr. Palmer received his Ph.D. in Bioengineering from The Pennsylvania State University in Hershey, PA, and obtained postdoctoral training at The University of Vermont. Dr. Palmer joined the faculty of the University of Vermont in 2009.

My lab focuses on examining contraction and relaxation function in cardiac muscle. While contraction function is clearly important for the heart to effectively drive blood through the vasculature, relaxation function is just as important to assure filling of the heart chambers with plenty of blood. We apply several different techniques to examine the influence of calcium regulation and myofilament performance in cardiac muscle function, and we apply these techniques to various muscle systems including insect flight muscle, isolated cardiac myocytes and cardiac biopsy samples taken from patients undergoing cardiothoracic surgery. Zinc, Zinc and Still More Zinc Zinc content in the serum and/or heart is abnormally low in humans with heart failure or other conditions such as diabetes, hypertension, coronary artery disease or myocardial infarction. Amazingly, cardiac zinc content positively correlates with ejection fraction in humans with coronary artery disease (r=0.428, P<0.05; Oster et al. Eur Heart J. 1993). Elevated cardiac zinc status also preserves cardiac function in the face of oxidative stress associated with ischemia/reperfusion or diabetes. Zinc most likely provides cardioprotection and improves cardiac function through its effects on Ca²⁺ regulation, myofilament force-production and/or proximal second messengers. It has also been suggested that zinc can act as a messenger of gene expression. Our laboratory focuses on the effects of cardiac zinc status on Ca²⁺ regulation, myofilament function and gene regulation. Zinc and Calcium Regulation in Cardiac Myocytes Through simultaneous detection of the intracellular concentrations of Zn²⁺ and Ca²⁺ in cardiac myocytes, we (namely Ting) are able to examine the interaction between Zn²⁺ and Ca²⁺ regulation in heart muscle. See the accompanying figure, which demonstrates how Zn²⁺ affects cardiomyocyte performance. Surprisingly little is known about cardiac myocyte regulation of Zn²⁺ or about its interaction with the Ca²⁺ regulation. Almost all that is known is that extracellular Zn²⁺ passes readily through the sarcolemmal L-type channel and competitively inhibits the inward Ca²⁺ current. Relaxation function after extracellular Zn²⁺ removal, however, remains enhanced and cannot be explained by effects on inward calcium current. It appears then that Zn²⁺ competes for or modulates the function of other Ca²⁺ regulatory proteins. We (Ting again) are testing the hypothesis that [Zn²⁺]int improves cardiac diastolic function by lowering Ca²⁺ load in the sarcoplasmic reticulum and/or enhancing Na⁺-dependent Ca²⁺ efflux, thus ultimately lowering total intracellular calcium content.