The mode of action of some drugs and chemicals used to treat hypertension or as muscle relaxants

The thesis is divided into two parts as follows:- Part I - Studies on the effect of certain drugs upon the flux of calcium, potassium and sodium ions in skeletal muscle. Part II - Studies on the pharmacology of petaline chloride, a convulsant alkaloid from Leontice leontopetalum Linn. Part I - Studies on the effect of certain drugs upon the flux of calcium, potassium and sodium ions in skeletal muscle. In the isolated frog sartorius muscle, depolarising and contracture producing drugs including suxamethonium, decamethonium, nicotine, neostigmine and ryanodine significantly increased the uptake of calcium-47 and sodium-24 hut depressed the uptake of potassium-42, Suxamethonium, nicotine, neostigmine and ryanodine also caused an increased release of calcium-47 and potassium-42 from the sartorius muscle. Decamethonium increased the release of potassium-42. Edrophonium depressed the uptake of calcium-47 and potassium- 42 and increased the release of calcium-47. Carbachol increased the release of potassium-42, Protoveratrine A and protoveratrine B depressed the uptake of calcium-47. Non-depolarising drugs - tubocurarine and gallamine - did not cause any significant change in the uptake of calcium-47, potassium-42 or sodium-24 or in the release of calcium-47 and potassium-42. It is concluded that when depolarising or contracture producing drugs are used, calcium ions may become more mobile being dissociated from combination with a carrier or displaced from a site on the cell membrane. This may result in the breakdown of barriers which retain potassium ions within the cell and sodium ions outside. Part II - Studies on the pharmacology of petaline chloride, a convulsant alkaloid from Leontice leontopetalum Linn. The alkaloidal salt petaline chloride, obtained from the tubers of Leontice leontopetalum Linn is a potent convulsant and is apparently 5 to 7 times as potent as leptazol and one-third as active as picrotoxin. At lower dose levels it appears to reduce the convulsant activity of leptazol and apparently gives some protection from electrically induced seizures. It has tubocurarine-like muscle relaxant properties and depresses both patellar tendon and crossed extension reflexes. It causes a fall in the blood pressure in anaesthetised animals and increases the rate, force and amplitude of the beat of isolated cardiac muscle depressed in a low calcium medium. It also antagonises the effect of different spasmogens on isolated smooth muscle preparation. It is concluded that because of its powerful convulsant action the use of petaline chloride is of dubious value in the treatment of epilepsy, but its pharmacological properties which includes muscle relaxant activity give some apparent basis for its use in folk medicine