Shaheen Sharaf Shah, Muzammil Hasan Najmi.
Role of Histamine H2 Receptors in Regulation of Respiratory Muscle Tone in the Guinea Pig.
J Rawal Med Coll Jan ;5(1):13-5.

Histamine is capable of producing both, contraction and relaxation of the respiratory smooth muscle by acting on Hi and Hz receptors respectively. In this study, the role of Hz receptors in normal and ovalbumin-sensitized lung parenchyma of the guinea pig was evaluated. Dimaprit, an Hz agonist, produced dose-dependent relaxation of the normal and sensitised lung parenchyma. Cimetidine, an H2 antagonist, produced contractions in both the normal and sensitised tissue. The findings support a physiological role of Hz receptors in regulation of normal airway resistance in the guinea pig.

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