Effects of nicotine and tyramine on contractile activity of the colon,

Contractile activity of the descending colon of the anesthetized dog was monitored with strain gage force transducers. Nicotine and tyramine caused primarily a relaxation of the circular and longitudinal muscle. A secondary stimulation frequently followed the inhibition. Adrenalectomy partially antagonized the effects of nicotine. Xylocholine and reserpine petreatment reduced the early portion of the inhibitory response to nicotine. Hexamethonium or a combination of adrenalectomy with either xycholine or reserpine pretreatment abolished the effects of nicotine. The effects of tyramine were antagonized by cocaine and reserpine-pretreatment. Tolazoline and propranolol (in combination) reduced the effects of both nicotine and tyramine. We conclude that both nicotine and tyramine relaxed the colon by releasing catecholamines. Nicotine caused release from the adrenal glands and adrenergic nerve endings; tyramine produced release from the adrenergic nerve endings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32663/1/0000028.pd

Rate and Volume of Intermittent Enteral Feeding

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141999/1/jpen0125.pd

Kesehatan Wanita Diatas umur 40 tahun

vii. 170 hlm.; ill.; 18 c

Calcium-induced contraction and contractile protein of gallbladder smooth muscle after high-cholesterol feeding of prairie dogs

Feeding a high-cholesterol diet to prairie dogs causes a reduction in contractile responses of gallbladder smooth muscle from these animals. In this study, the influence of cholesterol feeding on the contractile response to calcium and on the concentration of the contractile proteins actin and myosin was determined. Strips of gallbladder smooth muscle, at their optimal length for tension development, were stimulated maximally with carbachol. Then the muscle cell membranes were made permeable and strips were exposed to a maximally effective concentration of calcium. Strips from cholesterol fed animals developed less stress than those from control animals under all conditions. The concentration of actin and myosin was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. There were no differences in the concentrations of either protein between the cholesterol-fed and control animals. Our results indicate that the decreased contractile response seen in muscle from cholesterol-fed animals is not due to alterations in membrane excitation, excitation-contraction coupling, or in total contractile protein

Influence of autonomic drugs on the motility of the sphincter of Oddi in the opossum

We have evaluated the effect of various autonomic drugs on the electromyographic activity of the sphincter of Oddi and the small intestine of seven opossums. Hexamethonium bromide and atropine sulfate abolished and bethanechol increased the frequency of spike bursts in the sphincter of Oddi and duodenum. Phenylephrine and epinephrine increased the number of spike bursts in the sphincter of Oddi after a short period of stimulation. No spike potentials were seen in the duodenum after infusion of norepinephrine. Clonidine and dobutamine decreased spike burst activity in the sphincter of Oddi and duodenum. Terbutaline also decreased the frequency of spike bursts in the sphincter of Oddi but did not change the number in the duodenum. Prior infusion of antagonists blocked partially or totally the effect of all respective agonists except for yohimbine, which did not inhibit the effect of clonidine. These findings suggest that the sphincter of Oddi may have cholinergic, alpha 1, alpha 1, beta 1 and beta 2-adrenergic receptors. Cholinergic agonists stimulate and alpha 2, beta 1 and beta 2-adrenergic agonists inhibit the motility of the sphincter of Oddi and the small intestine. Alpha-adrenergic agonists stimulate the motility of the sphincter of Oddi and inhibit the motility of the small intestin