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Hyperresponsiveness of resistance vessels has been described in various vascular beds of spontaneously hypertensive rats perfused with artificial medium. This change has been attributed to altered vascular dimensions secondary to the development of hypertension. To test the possibility that true changes in sensitivity might contribute independently to(More)
The mechanism of sustained hypertension in spontaneously hypertensive rats has not been elucidated. In the present investigation, vasoconstrictor responses to a variety of neurogenic and humoral interventions were studied in the perfused hindquarters of Okamoto spontaneously hypertensive rats and normotensive Wistar rats. In addition, central sympathetic(More)
Systemic arterial pressure of spontaneously hypertensive rats (SHR) were not detectably different from control rats prior to 3 weeks of age. Arterial pressure was elevated in SHR at 4 weeks compared to Wistar-Kyoto rats. Thus, the term 'prehypertensive stage' should probably be reserved for animals less than 1 month of age when this model is examined.
1. Long-term changes in the function and structure of arteries and veins in response to an elevation in arterial pressure have been studied in the rabbit after partial abdominal aorta constriction. 2. Transient changes occur in the vasculature in association with the rise in arterial pressure. 3. The dominant change seen after arterial pressure elevation(More)
Factors which play a primary role in the initiation and development of hypertension in spontaneously hypertensive rats (SHR) are incompletely defined. To test the possibility that early changes in vascular function play a primary etiologic role, hindquarters of 3-week-old SHR and Wistar-Kyoto normotensive rats (WKY) were perfused at constant flow with(More)
Acetylcholine acts via presynaptic receptors to inhibit adrenergic neurotransmission in vascular tissue. To test the possibility that this modulation might be altered by hyperactivity of the sympathetic nervous system, rats were exposed to cold stress for 5 days. Rat caudal (tail) arteries were excised, cannulated and perfused at constant flow. Responses to(More)
The regulation of sperm transport through the Wolffian duct of male amphibians is poorly understood. These experiments were conducted using rough-skinned newts (Taricha granulosa) to determine if Wolffian ducts are capable of contracting in vitro and, if so, to characterize the contractile responses to acetylcholine (ACh), norepinephrine (NE), and(More)
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