Physiology and Pharmacology Essay Example | Topics and Well Written Essays - 1500 words

Physiology and Pharmacology - Essay Example The results of Schild analysis reveal that the drug homatropine is a competitive antagonist for acetylcholine, both competing exclusively for the muscarinic type cholinergic receptors. The Schild plot slope derived has a perfect unity value leading strongly to this conclusion. This also reveals that both agonist and antagonist compete exclusively for the same subtype of receptors without either getting involved with any other subtypes. The report concludes that this research has been relatively successful and thinks that this is of some value as it is highly essential to use such research as this to disclose the particular nature of the drug so that its pharmacology can be successfully implemented. Cholinergic receptor cell types are two – muscarinic and nicotinic. The muscarinic receptors, so called because of their response to muscarine, are to be found mainly in the post-ganglionic parasympathetic effector sites and also in the autonomic ganglion and adrenal medulla. In the latter parts of the nervous system they modulate nicotinic receptor mediated effects (Brown and Taylor, 1996, pp. 142-143). Atropine (dl-Hyoscyamine) and the semi-synthetic homatropine (isopto-atropine) are known muscarinic receptor anatagonists that are usually tertiary amines well able to be absorbed and infiltrate the central nervous system. Nevertheless, they can be converted into the quarternary form by addition of a methyl group to the nitrogen. In this form they are more potent as muscarinic blockers and have increased ganglionic blocking action. Permanently charged quarternary agents do not significantly intrude into the CNS and have limited action there (Brown and Taylor, 1996, pp. 149-150). The atropine/homatropine muscarinic receptor type antagonists have specific depolarization (late EPSP) action in autonomic ganglia. The molecular effects are stimulation of phospholipase C (PLC) with formation of inositol-1, 4, 5 triphosphate () and