1. Medical Physiology Department, College of Medicine, King Khalid University, Abha, KSA;
2. Medical Physiology Department, College of Medicine, Mansoura University, Mansoura, Egypt;
3. Medical Physiology Department, College of Medicine, Khartoum University, Khartoum, Sudan;
4. Medical Physiology Department, College of Medicine, Menoufia University, Al Minufya, Egypt