Heart-Rate Response to Sustained Hand Grip: Comparison of the Effects of Cardiac Autonomic Blockade and Diabetic Autonomic Neuropathy

Abstract

1.The heart-rate response during sustained hand grip was studied in four normal subjects before and after intravenous atropine, propranolol and combined cardiac autonomic blockade with both drugs. The results suggest that the increase in heart rate during the first 30 s is due to parasympathetic withdrawal, whereas the further increase between 30 s and 180 s is probably mediated by a combination of parasympathetic withdrawal and sympathetic stimulation.2. The increases in heart rate during each minute of sustained hand grip were compared in 26 normal subjects, 37 diabetic subjects without and 24 diabetic subjects with proven autonomic neuropathy. In the diabetic subjects with autonomic neuropathy the increase in heart rate during the first minute was impaired, whereas the increases during the second and third minutes were similar in all three groups.3. The initial increase in heart rate over the first 30 s of hand grip and the later increase between 30 's and 180 s were compared in nine normal subjects, ten diabetic subjects without and six diabetic subjects with autonomic neuropathy. The increase during thc first 30 s was impaired in the diabetic subjects with autonomic neuropathy, whereas the later phase of the response was similar in all three groups.

The Effect of Age on the Cardiovascular Responses to Isometric Exercise: A Test of Autonomic Function

“…Analysis of data with regard to time dem onstrates that the biphasic pattern of the heart rate and time response in the young subjects during fatiguing isometric exercise is similar to that previously described [Freyschuss, 1970;Martin, 1974;Hume, 1979]. Thus old age does not alter the characteristic pattern of the response.…”

“…There is an initial rapid increase due to withdrawal of cardiac parasympathetic activity, followed by a further increase probably due to cardiac sympathetic stimulation [Freyschuss, 1970;Martin, 1974], A reduced heart rate response to the early phase of parasympathetic with drawal was shown in diabetic patients with autonomic neuropathy [Hume, 1979]. The blood pressure response seems to be predom inantly mediated through the peripheral asympathetic system [Freyschuss, 1970].…”

Haemodynamic response to an isometric exercise test in obese patients: Influence of autonomic dysfunction

“…It was sustained until the ®fth minute by two-thirds of the patients. During the handgrip test, the acceleration in HR at the ®rst minute, which is clearly related to parasympathetic withdrawal, 14 was signi®cantly higher in the PS 7 patients as compared to age-matched controls ( Figure 2). This suggests an increase in cardiac vagal tone which may contribute to the decrease in resting HR in these patients.…”

“…The test was performed with a dynamometer by a subject in a sitting position for 10 min, as previously described. 14,18 For each subject, the maximal voluntary contraction was ®rst determined. The subject was then asked to maintain 30% of the maximal handgrip contraction for 5 min, while breathing quietly at the same rate as at rest.…”

“…12,13 In diabetic patients with clinically overt autonomic neuropathy, the increase in HR during the ®rst minute was found to be impaired, whereas the increase during the second and third minutes was unchanged. 14 Cardiovascular responses to exercise appeared also to be impaired in diabetic patients with subclinical autonomic neuropathy. 15 ± 18 This point has not yet been studied in nondiabetic obese patients.…”