The Effects of an Herbal Extract SPOO2P on Vascular Relaxation Responses

Hypertension affects approximately 50 million people in the U.S. and about one billion worldwide. SPOO2P (PhytoPharmacon, LLC, Durham, NC) is a purified botanical extract. We have reported that oral administration of SPOO2P reduced arterial pressure of anesthetized hypertensive rats. In addition, the contractile responses to endothelin‐1 were reduced by SPOO2P in aorta rings. Our current study looked at the effects of SPOO2P on vessels pre‐contracted with either phenylephrine (Phe) or KCl. In vitro responses of aorta rings from 16‐wk Sprague Dawley rats were measured with force displacement transducers coupled to tissue force analyzers (Micromed, Louisville, KY). Our protocols consisted of pre‐contraction with either Phe or KCl followed by increasing bath concentrations of the extract, SPOO2P. Our results indicate that SPOO2P causes relaxation of aortic rings that have been either contracted with KCl or with Phe. However when the vascular endothelium was removed the relaxation caused by SPOO2P persists in aortic rings pre‐contracted with KCl, but was significantly decreased (by 80%) in aortic rings contracted with Phe. These data suggest that SPOO2P may cause relaxation via two mechanisms: 1) by inhibition of voltage‐gated Ca2+ channels, and 2) by release of a vasodilator (possibly nitric oxide) from the vascular endothelium. Supported by a grant from the University of Louisville.