VIP and its homologues increase vascular conductance in certain endocrine and exocrine glands.
The effects of vasoactive intestinal peptide (VIP) and related structural homologues on tissue vascular conductances were investigated in anesthetized male rats. VIP, peptide histidine isoleucine (PHI), secretin, growth hormone-releasing factor (GHRF), gastric inhibitory peptide (GIP), or saline was infused intravenously over 4 min. Tissue blood flows were measured during this time by use of 141Ce-labeled microspheres. Regional blood flows were normalized for any change in mean arterial blood pressure during infusions, and results were expressed in terms of tissue vascular conductance (C). Circulating thyrotropin (TSH), triiodothyronine (T3), and thyroxine (T4) levels were determined before and at 20 min and 2 h after treatment. Marked increases in thyroid, pancreatic, and salivary gland vascular Cs occurred during peptide infusions with the order of potency (VIP greater than PHI greater than secretin greater than GHRF greater than GIP) correlating with the degree of structural homology to VIP. PHI and secretin produced maximal increases in vascular Cs, which were the same as those obtained with VIP. Circulating TSH, T3, and T4 levels were not different from values in saline-infused rats after peptide treatments that caused striking increases in thyroid vascular C. In the adrenal, kidney, and testis, VIP and its homologues had little to no effect on vascular Cs. We subsequently measured regional vascular Cs during VIP infusions in the presence or absence of secretin.(ABSTRACT TRUNCATED AT 250 WORDS)
Huffman
L J
LJ
Department of Physiology, West Virginia University Medical Center, Morgantown 26506.
Connors
J M
JM
Hedge
G A
GA
D000311:Adrenal Glands / Q000098:blood supply* / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D005768:Gastrointestinal Hormones / Q000494:pharmacology*; D007668:Kidney / Q000098:blood supply* / Q000187:drug effects; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology*; D010179:Pancreas / Q000098:blood supply* / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012039:Regional Blood Flow / Q000187:drug effects; D012469:Salivary Glands / Q000098:blood supply* / Q000187:drug effects; D013329:Structure-Activity Relationship; D013737:Testis / Q000098:blood supply* / Q000187:drug effects; D013961:Thyroid Gland / Q000098:blood supply* / Q000187:drug effects; D014660:Vasoactive Intestinal Peptide / Q000031:analogs & derivatives* / Q000494:pharmacology*
D005768:Gastrointestinal Hormones; D009479:Neuropeptides; D014660:Vasoactive Intestinal Peptide