Heart rate control in diabetic rabbits: blunted response to isoproterenol

Abstract

To study the effects of chronic diabetes on heart rate and adrenergic responsiveness we compared unanesthetized diabetic rabbits, 10-13 mo after alloxan monohydrate injection, to age-matched controls. There were no significant differences found between groups for body or heart weight. Both resting and intrinsic heart rate (the latter obtained after atropine sulfate and propranolol HCl) were similar. In addition, serum and left ventricular epinephrine and norepinephrine concentrations as well as left ventricular beta-receptor density and affinity were unchanged in diabetic animals. Heart rate responses to isoproterenol were blunted in diabetics at the three highest doses. Base-line mean blood pressure was modestly lower in diabetic rabbits, and parallel declines in pressure for both groups were observed in response to isoproterenol. The diminished heart rate response to isoproterenol in diabetic rabbits may be due to diminished myocardial sensitivity to catecholamines, possibly combined with altered baroreceptor reflexes. These experiments may provide an explanation for the blunted heart rate response to exercise described in human diabetics.

Peripheral 5-HT1Aand 5-HT7Serotonergic Receptors Modulate Parasympathetic Neurotransmission in Long-Term Diabetic Rats

“…This agent, in our experiments, did not modify heart rate, as previously indicated by Lee et al [25], Zola et al [26], and Howarth et al [27]. …”

Ocular and systemic reactivity to isoprenaline in patients with insulin‐dependent diabetes mellitus

“…As PPA is principally a function of stroke volume and arterial capacitance, the blunted response in PPA observed in the present study most probably reflects a reduced inotropic response to isoprenaline, which corroborates findings in isolated rat hearts [7,23]. The absence of heart rate changes in IDDM patients on the other hand reflects the altered chronotropic response to isoprenaline [24]. Again, the diminished sinus node sensitivity to catecholamines in diabetes might contribute to this effect [6,25].…”

Rodent models of diabetic cardiomyopathy

“…Fein et al, 1985;Zola et al, 1988 BB rat Rodrigues and McNeill, 1990;Broderick and Hutchison, 2004;Broderick and Poirier, 2005 Type 2 diabetes Goto-Kakizaki rat Desrois et al, 2004a;Desrois et al, 2004b KK A y mouse Ye et al, 2004 NOD, non-obese diabetic.…”