Aldosterone is a hormone produced in the zona glomerulosa and is known to be stimulated by several hormones. ANP is known to inhibit the production of individual cells of the zona glomerulosa. This study is to see if that same affect occurs when tissue sections of the zona glomerulosa is used. Aldosterone levels were measured by an ELISA technique after 24 and 48 hours' growth, with ANP administered to the variable group after 24 hours at concentrations of 240 pg/mL and 480 pg/mL. The samples taken after 48 hours were compared to the samples taken after 24 hours, to determine a percent decrease of aldosterone production. At a concentration of 240 pg/mL of ANP, a decrease in aldosterone production of 17.4% was found in the control group versus a decrease of 25.3% in the variable group containing ANP (p = NS). However, when the concentration of ANP was increased to 480 pg/mL, the variable group decreased 54.3% compared to a 35.2% decreased in the control (p = less than 0.0005). By comparing the percent decrease of aldosterone production, a dose-responsive curve became apparent.