This is the peer reviewed version of the following article: Iyinikkel, J., and Murray, F. (2018) GPCRs in pulmonary arterial hypertension: tipping the balance. British Journal of Pharmacology, 175: 3063–3079., which has been published in final form at DOI: 10.1111/bph.14172. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.