<prompt> Histamine causes:HypertensionVasoconstrictionVasodilationTachycardia  <response>: The main actions of histamine are: VasodilationIncreased vascular venular permeabilityItching PainStimulation of mast cells and basophils also releases products of arachidonic acid metabolism including the release of slow reacting substances of anaphylaxis SRS-As. The SRS-As consist of various leukotrienes LTC4, LTD4 and LTE4.Mohan H. Textbook of pathology. Jaypee Brothers Medical Publishers; 2015. Edition 7. Page 123 