. A text-book of practical therapeutics, with especial reference to the application of remedial measures to disease and their employment upon a rational basis . on the spinal cord itincreases reflex activity, and for thisreason is said to make people ner-vous. It is important to remem-ber that it has no effect on brainprotoplasm except to stimulate it,and that ultimately a brain drivenalong by caffeine breaks down bythe concentration of its energy forthe time being in one effort. Circulation.—Caffeine has beensupposed to increase the pulse-rateand blood-pressure by stimulatingthe heart-muscle,
. A text-book of practical therapeutics, with especial reference to the application of remedial measures to disease and their employment upon a rational basis . on the spinal cord itincreases reflex activity, and for thisreason is said to make people ner-vous. It is important to remem-ber that it has no effect on brainprotoplasm except to stimulate it,and that ultimately a brain drivenalong by caffeine breaks down bythe concentration of its energy forthe time being in one effort. Circulation.—Caffeine has beensupposed to increase the pulse-rateand blood-pressure by stimulatingthe heart-muscle, but from recentstudies in the United States andabroad it would seem probable thatthese changes are indirectly pro-duced and due solely to its stimu-lating action on the nervous system. Clinically, it certainly seemsto raise the blood-pressure in almost every instance where it isused. Kidneys, Tissue-waste, and Elimination.—Caffeine increasesdiuresis by causing dilatation of the renal vessels, particularly in theglomerules, and by preventing the absorbent action of the tubules. Italso exerts a direct stimulating influence on the secretory epithelium. Caffeine dilates bloodvessels of the Mal-pighian tuft (A) and stimulates the secretingepithelium lining the uriniferous tubules (B). 136 DRUGS. of the kidney, and therefore increases the amount of solids as wellas of the liquids in the urine. Upon tissue-waste the drug acts as adepressant, and is therefore a conservator of the tissues. It is oxidizedand destroyed in the body. Respiration.—Caffeine acts as a powerful stimulant to the respira-tory centre. Therapeutics.—Caffeine is a valuable cardiac stimulant and tonicas well as a renal stimulant. It acts equally wTell in cardiac and renaldropsies for this reason, and is an invaluable remedy in such useful is caffeine in cases of cardiac disease that it has largely sup-planted digitalis in the hands of some practitioners. In acute renalinflammation it is contraindica
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