Ninety healthy African-American men and women will be screened for an eight-day inpatient admission to the Clinical & Translational Research Center (CTRC). Sixty evaluable research participants will receive a seven day infusion of a predetermined dose of either PTHrP or PTH. Vital signs and blood and urine tests will be monitored frequently as per the study flow sheet. The starting dose of either peptide, 2 picomoles (pmols)/kg, will be given to three normal healthy subjects. Via a dose escalation protocol, the dose will be escalated in increments with successive groups of three subjects each, until early adverse effects (mild hypercalcemia, postural hypotension, tachycardia) are seen. This determined safe dose will then be given to 10 subjects. This dose escalation study design has been used in several prior studies at this institution in order to achieve a sustained mild serum hypercalcemia in the 10.5-11 mg/dL range in research studies. The investigators with this study are trying to determine a safe dose of PTHrP and PTH in African-American volunteers and determining if this population has the same physiologic response as Caucasians.