sentences:  Tachycardia and stimulation of the vasomotor center causes an increase in blood pressure.But, due to feed back regulation of the vasomotor center, there is fall in blood pressure due to vasodilation.Important muscarinic antagonists include atropine, Hyoscyamine, hyoscine butylbromide and hydrobromide, ipratropium, tropicamide, cyclopentolate, and pirenzepine.