Lin Y.-D.Hsu K.-L.EN-TING WUTsai M.-S.CHIH-HSIEN WANGChang C.-Y.KUO-CHU CHANG2020-06-302020-06-3020080014-2972https://www.scopus.com/inward/record.uri?eid=2-s2.0-49749145934&doi=10.1111%2fj.1365-2362.2008.01992.x&partnerID=40&md5=63a9986cbe708faa507f4164c5975ca5https://scholars.lib.ntu.edu.tw/handle/123456789/507168Background: Our team previously demonstrated arterial stiffening and cardiac hypertrophy in type 2 diabetic rats at 8 but not 4 weeks after being administered streptozotocin (STZ) and nicotinamide (NA). The present study focused on investigating the effects of type 2 diabetes on cardiac autonomic nerve function in the STZ- and NA-treated animals, using modern spectral estimation technique. Design: An autoregressive process was performed to each detrended signal of heart rate and systolic blood pressure measured in the 4- and 8-week STZ-NA rats with anaesthesia. The power of low-frequency and high-frequency oscillations was automatically quantified with each spectral peak by computing the residuals. The closed-loop baroreflex gain was estimated using the square root of the ratio between heart rate and systolic blood pressure powers in the low-frequency band. Results: Compared with the age-matched controls, both the 4- and 8-week STZ-NA diabetic rats had significantly decreased low-frequency oscillations of heart rate but not systolic blood pressure variability, showing a decline in baroreflex gain (0.451 ± 0.060 and 0.484 ± 0.056 vs. 1.196 ± 0.064 ms mmHg-1, P < 0.05). On the other hand, the low frequency-high frequency power ratio of the heart period was also diminished in the two diabetic groups, indicating a shift in sympatho-vagal balance of the heart control (0.472 ± 0.109 and 0.504 ± 0.090 vs. 1.857 ± 0.336, P < 0.05). Conclusions: The cardiac autonomic dysfunction in the absence of any significant changes in vascular dynamics, 4 but not 8 weeks after induction of type 2 diabetes, suggests that the diabetic autonomic neuropathy may precede arterial stiffening and cardiac hypertrophy in the STZ- and NA-treated rats. ? 2008 The Authors.en[SDGs]SDG3animal experiment; animal model; animal tissue; article; autonomic neuropathy; blood pressure variability; cardiovascular disease; controlled study; diabetic neuropathy; heart innervation; heart rate; high frequency oscillation; male; non insulin dependent diabetes mellitus; nonhuman; pressoreceptor reflex; priority journal; rat; regression analysis; streptozocin diabetes; sympathetic tone; systolic blood pressure; vagus tone; Animals; Autonomic Nervous System; Baroreflex; Blood Pressure; Cardiomegaly; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Heart Rate; Male; Rats; Rats, Wistar; Spectrum Analysisjournal article10.1111/j.1365-2362.2008.01992.x188377352-s2.0-49749145934