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Receptor Autoradiography Protocol for the Localized Visualization of Angiotensin II Receptors
Published on: June 7, 2016
Oxidative stress increases angiotensin receptor type I responsiveness by increasing receptor degree of aggregation
Titiwat Sungkaworn1, Yongwimon Lenbury, Varanuj Chatsudthipong
1Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand.
Abstract:
Oxidative stress and hyper-functioning of angiotensin II receptor type I (AT(1)R) are commonly observed in hypertensive patients but the relationship between oxidative stress and AT(1)R function is still unclear. We investigated the effects of H(2)O(2) treatment on AT(1)R-mediated intracellular calcium [Ca(2+)](i) signaling and its cell surface distribution pattern in HEK cells stably expressing EGFP-tagged rat AT(1)R using image correlation spectroscopy (ICS). Following H(2)O(2) treatment (50-800μM), [Ca(2+)](i) was significantly increased upon angiotensin II stimulation. Similarly ICS revealed a significant increase in degree of AT(1)R aggregation in H(2)O(2) treated group during Ang II activation but no difference in cluster density compared with untreated control cells or those with N-acetyl cysteine pretreatment. Thus, oxidative stress-induced AT(1)R hyper-responsiveness can be attributed by an increase in cell surface receptor aggregation state, possibly stemming in part from oxidant-related increase receptor-receptor interactions.
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