<prompt> Nitroglycerine exes beneficial effect in classical angina pectoris primarily byIncrease in total coronary blood flowRedistribution of coronary blood flowReduction of cardiac preloadReduction of cardiac afterload  <response>: nitrates are vasodilators mainly acting on the veins only. hence they are venous dilators therefore decrease the preload on the hea where as aerial dilators like hydralazine decrease the after load. Ref: KD Tripathi 8th ed. 