Integrative Nature and Time Course of Cardiovascular Alterations in the Diabetic Rat

Dowell, Russell T.; Atkins, Floyd L.; Love, Sandra

doi:10.1097/00005344-198603000-00026

Cited by 31 publications

(11 citation statements)

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“…Several previous studies carried out in vivo and in isolated heart preparations have demonstrated age‐dependent declines in HR, which may be partly due to changes in pacemaker activity of the heart as well as adrenergic control (Goldberg et al 1988; Schmidlin et al 1992; Irigoyen et al 2000). In diabetic rats, despite the rapid and dramatic reductions in HR, the mean arterial pressure tends to be well maintained by minimizing cardiac output reduction via slight increases in stroke volume and concomitant small increases in total peripheral resistance (Dowell et al 1986).…”

Section: Discussionmentioning

confidence: 99%

Long‐term effects of streptozotocin‐induced diabetes on the electrocardiogram, physical activity and body temperature in rats

Howarth¹,

Jacobson²,

Shafiullah³

et al. 2005

Experimental Physiology

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In vivo biotelemetry studies have demonstrated that short-term streptozotocin (STZ)-induced diabetes is associated with a reduction in heart rate (HR) and heart rate variability (HRV) and prolongation of QT and QRS intervals. This study investigates the long-term effects of STZ-induced diabetes on the electrocardiogram (ECG), physical activity and body temperature. Transmitter devices were surgically implanted in the peritoneal cavity of young adult male Wistar rats. Electrodes from the transmitter were arranged in Einthoven bipolar lead II configuration. ECG, physical activity and body temperature data were continuously recorded with a telemetry system before and following the administration of STZ (60 mg kg −1 ) for a period of 22 weeks. HR, physical activity and body temperature declined rapidly 3-5 days after the administration of STZ. The effects became conspicuous with time reaching a new steady state approximately 1-2 weeks after STZ treatment. HR at 4 weeks was 268 ± 5 beats min −1 in diabetic rats compared to 347 ± 12 beats min −1 in age-matched controls. HRV at 4 weeks was also significantly reduced after STZ treatment (18 ± 3 beats min −1 ) compared to controls (33 ± 3 beats min −1 ). HR and HRV were not additionally altered in either diabetic rats (266 ± 5 and 20 ± 4 beats min −1 ) or age-matched controls (316 ± 6 and 25 ± 4 beats min −1 ) at 22 weeks. Reduced physical activity and/or body temperature may partly underlie the reductions in HR and HRV. In addition, the increased power spectral low frequency/high frequency ratio from 4 weeks after STZ treatment may indicate an accompanying disturbance in sympathovagal balance. Treatment of young adult rats with streptozotocin (STZ) produces a diabetic state that is characterized by loss of weight, polydipsia, polyuria, glucosuria, polyphagia, hypoinsulinaemia and hyperglycaemia (Hakim et al. 1997). The pathophysiology of STZ-induced diabetes includes a cardiomyopathy that is frequently associated with contractile dysfunction and heart rhythm disturbances. Contractile dysfunctions, including reduced amplitude of contraction and prolonged time course of contraction and relaxation, have been frequently reported in myocytes from STZ-treated rats (Okayama et al. 1994;Yu et al. 1994;Ren & Davidoff, 1997;Howarth et al. 2001;Choi et al. 2002). Defective Ca 2+ signalling mechanisms, including reductions in L-type Ca 2+ channel current, depressed sarcoplasmic reticulum Ca 2+ uptake and release mechanisms, and reduced rate of Ca 2+ efflux on the Na + -Ca 2+ exchange, partly underlie these contractile defects (Lagadic-Gossmann et al. 1996;Chattou et al. 1999;Choi et al. 2002). Reductions in heart rate (HR) in isolated perfused heart (Li et al. 1989;Nicholl et al. 1991;Imai et al. 1991;Ravingerova et al. 1996;De Angelis et al. 2000;Nemeth et al. 2001) and spontaneous beating rate in right atria (Goyal & McNeill, 1985;Ramanadham & Tenner, 1986;Kofo-Abayomi & Lucas, 1988;Nagamine et al. 1989;Booth & Hodgson, 1993;Hicks et al. 1997;Sellers & Chess-Williams, 2000) from ...

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Section: Discussionmentioning

confidence: 99%

Long‐term effects of streptozotocin‐induced diabetes on the electrocardiogram, physical activity and body temperature in rats

Howarth¹,

Jacobson²,

Shafiullah³

et al. 2005

Experimental Physiology

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“…In STZ-induced diabetic rats, a decrease in HR (bradycardia) is one of the earliest signs of DM-related cardiovascular change (Dowell et al 1986, Ramanadham & Tenner 1986, Maeda et al 1995, Patel & Zhang 1995, Hicks et al 1998, Oliveira et al 1999, and is supposed to be originate in a diminution of the basal spontaneous pacemaker rate in the right atria after STZ treatment (Ramanadham & Tenner 1986, Hicks et al 1997. Although the mechanism of the diminution is still unclear, it is possible that the lengthened action potential duration, which has been reported in right ventricular papillary muscles and left atrial myocardium Figure 2 Heart rate in EXP and CONT rats.…”

Section: Discussionmentioning

confidence: 99%

“…Earlier studies have indicated a decreased resting heart rate (HR) in STZ-induced DM rats, and functional and morphological impairments in the cardiovascular system have been mentioned in these animals (Dowell et al 1986, Ramanadham & Tenner 1986, Maeda et al 1995, Patel & Zhang 1995, Hicks et al 1998, Oliveira et al 1999, Pacher et al 1999. Nevertheless, in a recent study on unrestrained conscious STZ-induced DM rats, a significant decrease in the resting HR, which had already occurred precipitously during the first 2 weeks after STZ administration, was partially reversed to an increase caused by insulin treatment (Hicks et al 1998).…”

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confidence: 99%

The acute effects of insulin on the cardiorespiratory responses to hypoxia in streptozotocin‐induced diabetic rats

Saiki

Seki

Furuya

et al. 2005

Acta Physiologica Scandinavica

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“…The hypertrophic response is an adaptive mechanism of the myocardium in order to compensate for decreased functional capacity [13]. On the other hand, diabetic cardiomyopathy has also been associated with decreased EF and ventricular dilatation in rats and humans, which, however, occurs more frequently with longer duration of diabetes [1,3,43].…”

Section: Discussionmentioning

confidence: 99%

Contributions of endothelin‐1 and sodium hydrogen exchanger‐1 in the diabetic myocardium

Hileeto

Cukiernik

Mukherjee

et al. 2002

Diabetes Metabolism Res

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Integrative Nature and Time Course of Cardiovascular Alterations in the Diabetic Rat

Cited by 31 publications

References 0 publications

Long‐term effects of streptozotocin‐induced diabetes on the electrocardiogram, physical activity and body temperature in rats

Long‐term effects of streptozotocin‐induced diabetes on the electrocardiogram, physical activity and body temperature in rats

The acute effects of insulin on the cardiorespiratory responses to hypoxia in streptozotocin‐induced diabetic rats

Contributions of endothelin‐1 and sodium hydrogen exchanger‐1 in the diabetic myocardium

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