Title

BKCa Channel Expression and Functional Regulation in Type II Diabetic Human Pulmonary Arterial Smooth Muscle Cells

Date of Award

5-2018

Degree Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

Shu Zhu MD, PhD

Second Advisor

Richard E White PhD, FAHA

Third Advisor

Abigail Hielscher PhD

Abstract

The large conductance, voltage- and Ca2+- activated K+ (BKca) channels, composed of alpha (a.) and beta(~) subunits, are highly expressed in vascular smooth muscle cells including pulmonary arterial smooth muscle cells (PASMCs). Cyclic AMP and cyclic GMP are second messengers that regulate BKca channels in P ASMCs. They are known mediators of smooth muscle vasodilation. BKca channels play an important role in regulating the membrane potential of PASMCs. The opening of BKca channels causes membrane hyperpolarization and pulmonary vasorelaxation, while closing ofBKca channels leads to membrane depolarization and pulmonary vasoconstriction, which is considered one of the most crucial factors that cause the development of pulmonary hypertension (PH). PH is caused by increased pulmonary arterial resistance and pressure and can eventually lead to the right-side heart failure and death. Clinical evidence shows that patients with diabetes have a high risk of developing PH, however, the mechanism is nnclear. Our previous studies showed that diabetic porcine P ASMCs expressed both BKca channel a and ~ 1 subunits with an increased expression of the a subunit comparing to the normal porcine P ASMCs. cAMP generation was measured in normal and diabetic porcine PASMCs. Forskolin, an adenylyl cyclase activator, increased cAMP generation in diabetic porcine PASMCs, but to a lesser extent when compared to normal porcine PASMCs. Current study focused on the expression and regulation of BKc, channels in type II diabetic human PASMCs (D2HPASMCs). Western blot showed an increased expression of a subunits and decreased expression of~ 1 subunits in D2HPASMCs comparing to normal human P ASMCS (HPASMCs). Forskolin increased cAMP generation in HPASMCs in high glucose media (HG), but to a lesser extent when compared to HPASMCs in normal glucose media. Collectively, the results showed that altered expression and functional regulation of BKc, channels in P ASMCs may lead to the development of PH.

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