INHIBITION AND FACILITATION OF LACRIMAL FLOW BY β‐ADRENERGIC DRUGS

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Abstract
The effects of adrenergic .beta.-stimulating and .beta.-blocking compounds on tear flow were studied in conscious rabbits with a modified Schirmer technique. The tear flow was significantly increased by the unselective .beta.-adrenergic agonist isoprenaline and by the selective .beta.1-agonist H 80/62 (racemic Prenalterol, (.gamma.)-1-(p-hydroxyphenoxy)-3-(isopropylamino)-2-propanol). The effects of the agonists were blocked by the unselective .beta.-adrenergic antagonist propranolol (Inderal) and by the selective .beta.1-antagonist metoprolol (Seloken, Lopressor). The .beta.-receptors involved in the regulation of the tear flow appeared to be of the .beta.1-type. The anatomical location of these .beta.-receptors is at present unclear but in vitro experiments performed on the rabbit lacrimal glands indicated that the receptors were probably not located on cholinergic nerve-endings as the release of acetylcholine was not influenced by isoprenaline.