Abstract
Neural lobe blood flow (NLQ) increases 210% 3–5 minutes after reducing arterial blood pressure from 120 to 80 mmHg and returns to control levels after 10 minutes sustained hypotension. The initial spike appears to be coupled with a transient rise in arginine vasopressin (AVP). In this study we examined neurohypophyseal autoregulation using a method of reducing cerebral perfusion pressure (CPP) that does not stimulate AVP release. Regional cerebral blood flow (rCBF) was measured by the microsphere method in 5 pentobarbital anesthetized dogs. Injections were made during normotension and 3, 5, 10 and 15 minutes after reducing CPP to 80 mmHg by increasing intracranial pressure (ICP). Plasma AVP was measured by radio immunoassay. Average cerebral blood flow was not different from control levels at any time during reduced CPP. Neither NLQ (503 ± 120, 441 ± 128, 544 ± 141, 578 ± 158 and 458 ± 99 1/min/100gm), nor AVP (9 ± 1, 8 ± 2, 10 ± 3, 9 ± 2 and 10 ± 3 pg/ml) changed during the period of reduced CPP. These findings demonstrate that NLQ is autoregulated. They suggest that multiple factors determine the overall NLQ response to a change in CPP. The initial spike seen during hemorrhage appears to be the result of transient changes in AVP neurosecretory rate. NLQ transients obtained using methods of lowering CPP that do not trigger AVP release show no spike component. Supported by: NS-20020.
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Hanley, D., Wilson, D., Traystman, R. et al. 185 NEUROHYPOPHYSEAL AUTOREGULATORY RESPONSE TO INCREASED INTRACRANIAL PRESSURE. Pediatr Res 19, 141 (1985). https://doi.org/10.1203/00006450-198504000-00215
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DOI: https://doi.org/10.1203/00006450-198504000-00215
