ACTION OF CHOLINESTERS ON SENSORY NERVE ENDINGS IN SKIN AND MUSCLE

1. This is a review of the literature on the subject of the effects of cholinesters and their agonists on sensory nerve endings. 2. The present-day view is that acetylcholine (ACh) has an excitatory action on some cutaneous receptors. Responses appear to be limited to receptors served by small myelinated and un-myelinated axons where responsiveness is multimodal; that is, the receptors are activated by noxious thermal and mechanical stimulation. 3. The possible role played by acetylcholine in sensory transduction processes is discussed, as are other explanations for the presence of nicotinic cholinergic receptors on the terminals of cutaneous receptors. 4. The excitatory action of ACh and succinylcholine (SCh) on muscle spindles is described. Two possible mechanisms are considered: a direct depolarizing action on the nerve terminals and indirect excitation, brought about by a contracture of the intrafusal fibres on which the sensory endings lie. 5. The technique of using SCh in combination with fusimotor stimulation is described. This has provided new information about the internal workings of muscle spindles. Brief mention is also made of the action of SCh on tendon organs and joint receptors. 6. It is concluded that a direct action by cholinesters is restricted to receptors served by small axons with multimodal functions. The precise role of such an action remains the subject of speculation. Possible clinical significance is discussed.     

Iopamidol arteriography: discomfort and pain

A double-blind, randomized study was performed to compare discomfort and pain associated with the use of iopamidol and Hypaque (diatrizoate sodium and diatrizoate meglumine) during iliofemoral runoff arteriography in 33 patients. Iopamidol caused substantially less discomfort and pain. The evaluation was helped by audiotaping the study and comparing patients' vocal responses to injections of these materials.     

Overt albuminuria predicts diabetic retinopathy in Hispanics with NIDDM

Non-insulin-dependent diabetes mellitus (NIDDM) occurs with a higher frequency in Hispanic as compared with non-Hispanic whites. It also appears that there is a higher prevalence of diabetic nephropathy in the Hispanic population when compared with non-Hispanic whites. In the current study, 144 Hispanics and 671 non-Hispanic white NIDDM subjects were studied to determine the possible association of various risk factors and diabetic complications, including overt albuminuria, with diabetic retinopathy. Stereoscopic retinal fundus photographs were obtained and graded by the University of Wisconsin Fundus Photographic Reading Center. We also sought to determine whether risk factors for retinopathy vary between Hispanics and non-Hispanic whites. In the total group, duration of diabetes, glycosylated hemoglobin, neuropathy, diastolic hypertension, use of insulin, and Hispanic ethnicity correlated with the presence of retinopathy. Controlling for severity and duration of diabetes, Hispanics had a significantly increased risk of retinopathy relative to non-Hispanic whites (OR = 2.13, 95% CI = 1.34, 3.37, P = 0.0013). Duration of diabetes and presence of neuropathy were significantly correlated with the presence of diabetic retinopathy in Hispanics and non-Hispanic whites. The presence of overt albuminuria (>200 microg/min), although not related to diabetic retinopathy in non-Hispanic whites, conferred a high risk for diabetic retinopathy in Hispanics (OR = 11.14, CI = 1.20, 103.39, P = 0.0339) independent of other risk factors. In summary, Hispanics with NIDDM have an increased prevalence of diabetic retinopathy when compared with non-Hispanic whites. In addition, overt albuminuria in the Hispanic subjects appears to be a powerful predictor of the diabetic retinopathy.