H1 Relate more to Muscarinic and 5HT 1-receptors • Smooth mm
• Endothelium (vascular)
• Brain (post-synaptic)
• Exocrine glands
H2 Relate more to Muscarinic and 5HT 1-receptors • Gastric mucosa (Parietal cells)
• Cardiac muscle cells
• Some immune cells (mast)
• Brain (post-synaptic)
H3 • Brain (presynaptic auto & hetero Rs)
• Myenteric plexus
• Other neurons
• Cardiovascular system
H4 40% homology with H3 • Eosinophils
Not closely related to any other • Neutrophils
• CD4 T-cells
• Leukocytes in BM, circulationg blood