1. Department of Medical Physiology, Makerere University College of Health Sciences, Kampala P.O. Box 7072, Uganda
2. Department of Obstetrics and Gynecology, School of Medicine, Makerere University College of Health Sciences, Kampala P.O. Box 7072, Uganda
3. Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
4. Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
5. Department of Physiological Sciences, School of Medicine and Health Sciences, Mulungushi University, Kabwe P.O. Box 80415, Zambia