Annually 9.6 million cardiovascular related deaths occur in developing countries. AT1 receptor antagonists such as Losartan™ block Ang II actions in vitro and in vivo, although the molecular mechanism remains unknown. The identification of putative AT1 receptor blockers in plants and their mode of action remain elusive. Molecular techniques such as Real-time PCR provides a reliable and accurate method for use in gene expression studies. This book looks at the vivo mechanisms of a plant compound, compared to a commercial hypertension drug Losartan™, by studying their effects on AT1 mRNA gene expression in rat cardiac tissue. Findings from this book illustrate that AT1 gene expression is related to the tissue-specific action of these drugs in salt-sensitive hypertension. Analyses and research from this book may assist in providing insight to those interested in molecular techniques specifically Real Time PCR used in medical research, to those interested in hypertension and research in this area.